The most frequent and serious problems in retroperitoneal tumor surgery are injury to large blood vessels and hemorrhage. Due to the large size of the tumor, the location of the tumor is deep, the blood vessels are pushed and squeezed, and due to the limitation of the incision is not big enough when separating the tumor, the compressed blood vessels are not easily revealed, so the blood vessels may be injured with little attention. Veins are easier to be damaged than arteries. In order to completely remove the tumor, the outer membrane of the artery immediately adjacent to the tumor can be separated, and generally the artery will not be broken. However, sometimes the artery is damaged due to long term pressure, and even if the outer membrane is separated, the vessel may be broken. The iliac artery, including the common and external iliac arteries, can be compressed by the tumor and pushed into an arch shape. In this case, in principle, we should try to separate the artery intact first, without doing resection anastomosis or grafting of the artery. However, the proximal and distal ends of the compressed artery should be freed and controlled first. Once the vessel is divided, the blood flow can be blocked to avoid massive bleeding. If the artery wall is severely damaged and the wall is easily torn during suture repair, the segment must be removed for vascular grafting. In our hospital, we encountered a case of simultaneous external iliac artery resection graft and sigmoid resection anastomosis, where the arterial anastomosis and the colonic anastomosis were close to each other. On the 7th postoperative day, a large amount of blood in the stool suddenly appeared, and the exploration confirmed that the two anastomoses were perforated, and a colostomy was performed to repair the vascular anastomosis. This complication might have been avoided if a piece of omentum had been used to separate the two anastomoses at the first surgery. When the external iliac vein is compressed during pelvic tumor surgery, there is a significant chance of splitting the vein, and the distal and proximal ends of the compressed vein should also be freed and controlled. Once the vein is divided, the vein must be blocked. After the tumor is removed, the repair of the vessel is considered. The repair of the iliac vein is more difficult and the chance of graft failure is high. Most of the veins in our hospital are ligated and restored after surgery by the establishment of side branches. Injury to the renal vein also occurs frequently. One side of the kidney can be pushed far away by the tumor, and the renal vein is stretched long and its direction is not perpendicular to the inferior vena cava, but almost parallel, so it is easy to be mistakenly injured during separation. If the kidney has been observed to be obviously displaced from the CT film, if we try to dissect the inferior vena cava first and go to the renal vein along the inferior vena cava, it is also a way to avoid damaging the renal vein. Once the renal vein is divided, most of them can be repaired under direct vision, if there is difficulty in repairing at that time, finger pressure can be used and then repaired after the tumor is removed. Injuries to the superior mesenteric vein and portal vein are less common. A large retroperitoneal tumor in the upper right can push and squeeze the superior mesenteric vein and can injure this vein. Therefore, there are many branches of the vein, and it is difficult to do adequate freeing and repair. Therefore, this vein should be avoided as much as possible during the operation. Once this vein is broken, do not panic to clamp it, but use non-invasive vascular forceps to clamp it together with part of the mesentery. After the tumor is free or removed, the vein can be repaired as appropriate. Improper suturing can often narrow the vessel and cause postoperative thrombosis. We have encountered a case in which the superior mesenteric vein was cut off and ligated by mistake, and then one of its branches was disconnected and turned upward to make anastomosis with the proximal end. Injuries to the inferior vena cava are also more common. Most commonly, they are seen in paragangliomas located between the inferior vena cava and the aorta. This tumor can severely push and crush the inferior vena cava. It is easy to injure this vein during dissection. However, repair of the inferior vena cava is not difficult, so the vein is wide and thick-walled, so it is not difficult to free and can be repaired by clamping with noninvasive vascular forceps, and stenosis is not easily formed after suturing. In other cases, such as tumors at the pelvic floor, the sacral plexus can be injured by inadvertent manipulation, which is often more difficult to handle. Because the tumor has not been removed in most cases, it is very difficult to stop the bleeding. Compression has to be used to stop bleeding. We have encountered some hospitals where this situation occurred and the tumor was not removed after filling with uterine gauze and was referred to our hospital. rupture and bleeding of the presacral vessels; 4. More than bleeding from the tumor bed after tumor resection. If the intraoperative bleeding of retroperitoneal tumor is large, such as more than 3,000ml, due to insufficient circulating blood volume, the patient will show symptoms of hemorrhagic shock such as decreased blood pressure and accelerated heart rate. The surgeon should remain calm at this time, when the cause of bleeding is unknown, do not blindly clamp in a panic, resulting in accidental injury to important large vessels or retroperitoneal organs, and the fissure of the large retroperitoneal vessels may crack bigger and bigger under the clamp of hemostatic forceps, bleeding more violent, endangering the life of the patient. If the bleeding is caused by the rupture of large blood vessel, it is usually not a big rupture, so the first assistant should be asked to lightly press on the rupture with fingers first, and do not try to repair before the tumor is separated from the blood vessel. Because the blood vessel is not yet free to a certain extent, it is extremely difficult to repair it, which will cause the rupture to tear bigger and finally fail, and the blood vessel will have to be sacrificed and the corresponding tissue will lose blood supply and be forced to be removed. Only after the tumor is separated from the vessel to a certain distance, the ruptured vessel can be controlled by non-invasive vessels and repaired by suturing under direct vision. When bleeding from the tumor donor vessels around the retroperitoneal tumor is identified, hemostatic forceps can be used to stop the bleeding, and sutures or ligatures can be applied. It is sometimes difficult to control presacral hemorrhage because the extraperitoneal tumor occupies almost all the space in the pelvic cavity, so the bleeding site cannot be well exposed and cannot be properly treated under direct vision. When the huge retroperitoneal tumor is cut down after a long and difficult operation, due to the large amount of bleeding and blood transfusion during the operation, many coagulation substances are lost, the coagulation function of the patient is very poor, and the bleeding from the tumor bed is sometimes difficult to control. The most effective and easy way to stop bleeding at this time is to fill and compress the wound with gauze or gauze pads, suture the incision, and end the surgery. However, it should be remembered that the number of gauze or gauze pads filled and compressed should be accurately recorded, and one end of the gauze should be placed outside the incision and removed after 3 days. Applying this method in our hospital, we have effectively controlled many such patients with intraoperative bleeding which is difficult to handle, and successfully removed the tumor and saved the patient’s life. In conclusion, as long as the occurrence of vascular injury can be avoided or reduced during surgery to minimize bleeding, the success of surgery can be ensured. Therefore, it is necessary to be familiar with the relevant anatomy, anticipate the possible displacement of blood vessels in each specific case, separate along the tumor envelope in strict accordance with the sharp anatomy, and make various preparations on how to deal with vascular injury if it occurs, so that the occurrence of complications may be reduced to a minimum.