Complex scars in children due to burns and other causes are often located in exposed areas. Since 2007, we have achieved satisfactory results in the treatment of complex scars in different parts of children using skin expansion techniques. 1. Psychological care of the children As the scarring in this group of children is caused by other diseases. Especially the children with burns experienced operations with certain pain such as debridement, skin grafting and drug exchange at a much earlier stage, and they have a strong fear of medical personnel. How to reduce the pain caused by the operation and gain the child’s cooperation became an important factor in the success or failure of the operation. Two of the leaking injection pots were caused by the child’s fear of agitation and the inconvenience of the operation. Our experience includes: communicating with the child’s parents to make them understand the advantages of the minimally invasive dilation technique, the inconvenience of multiple injections, and the key observations after the injection to dispel their nervousness; having an experienced nurse play games with the child during each injection, and giving the child small toys after the injection to eliminate his or her fear; and being gentle with the injection to avoid causing discomfort to the child. The youngest child we have successfully used the skin expansion technique is 3 years old. At this age, the child has the ability to communicate verbally and can tolerate relatively large procedures. For complex scars that are likely to cause or have caused developmental deformities in the affected area, we believe it is best to correct them before school age. 2. Surgical design and technique The dilator implantation should meet the aesthetic requirements. The design should take into full consideration the site and size of the lesion and the way of flap transfer in phase II. An unreasonable design often leads to the inability to transfer the expanded flap to the defect area efficiently. First of all, the site of the incision should be designed as far as possible within the normal tissue at the edge of the scar to ensure good healing of the incision. Initially we tend to design the incision within the scar or at the edge of the scar for fear of increasing scarring. This method has certain risks, one is that the incision is often difficult to heal due to poor blood flow, and the complex scar is often hard and thick, which makes it difficult to reveal and place dilators. Later, we changed the incision design to be in the normal tissue close to the scar, which is easy to operate and the wound heals well, and does not reduce the area used for dilating the flap. Also the expansion pot should not be designed inside the scar as much as possible. If the expansion pot must be placed inside the scar for reasons such as placing multiple dilators, it needs to be as close to the scar epidermis as possible, otherwise the injection pot will be easily displaced or have difficulty in water injection. Secondly, the expansion volume should be overdrawn, and the retraction of the flap cut and the length loss of the transfer should be calculated, and the expansion volume should generally be about 20% larger than the measured value, rather more than less. The lower the tension of the sutured flap, the smaller the postoperative scar. Again the injection pot must be well fixed when placed in the scar or near the joint area to avoid displacement or flip. Finally, drainage is placed according to the situation. 3. Injection method and precautions During the dilation process, we found that children have two characteristics compared to adults: (1) poor pain tolerance. (2) Rapid dilatation. 4.Complications and their prevention The main complications in this group include hematoma infection, dilator exposure and local necrosis of the flap. Infection may be caused by rejection of the organism, hair follicle infection, poor drainage, etc. The main cause of hematoma formation is incomplete hemostasis and dead space left behind. Intraoperative attention to the peeling level and thorough hemostasis, routine placement of drainage and pressure bandaging can prevent hematoma formation. Once the hematoma is formed, timely surgical exploration and drainage should be performed, and the cystic cavity should be flushed clean of blood clots and broken fat. To avoid flap necrosis and infection. The causes of flap necrosis are multiple, but poor blood flow is the most direct cause, so good design is the key, while prolonging the expansion cycle and intraoperative attention to avoid excessive tension can also prevent flap necrosis. Once postoperative flap cyanosis and other venous stasis manifestations are detected, early treatment can reduce the area of flap necrosis. Overall, the application of flap expansion provides a good means for early release of severe soft tissue deformities and developmental disorders in children with severe scar deformities caused by burns and other lesions, which is a landmark advance in the history of plastic surgery. However, there are still a series of questions about the appropriate expansion rate and the optimal age for surgery when soft tissue expansion techniques are used in young patients, and we believe that these questions will have more reasonable answers as we gain more experience.