Hemorrhagic cystitis: Hemorrhagic cystitis occurs in the early post-transplant period and is associated with the application of a large number of chemical agents, especially cyclophosphamide, during transplant pretreatment. Clinical manifestations include urinary urgency, frequency, painful urination and hematuria. Prevention: drink a lot of fluids during the input of cyclophosphamide, the volume of fluid intake (drinking water + infusion) should be above 3000 ml/m2 to ensure adequate urine output. Interstitial pneumonia: Cytomegalovirus is the leading pathogen. It can also be caused by other pathogenic microorganisms and immune damage. Clinical manifestations: shortness of breath, dry cough, elevated body temperature, progressive dyspnea, cyanosis, decreased oxygen saturation and partial pressure of oxygen. Precautions: After leaving the clean room, ventilate the room regularly to keep the air fresh, irradiate the room with ultraviolet light for 1 hour in the morning and evening, perform respiratory function exercises appropriately, limit visitors, increase and decrease clothing appropriately according to weather changes when going out, and bring a mask. If there is shortness of breath, coughing, coughing and other respiratory symptoms promptly inform the health care provider and take early treatment measures. Routinely draw blood to check for cytomegalovirus, and if it appears positive, insist on treatment regardless of symptoms. Drug prophylaxis is available with allicin, acyclovir, ganciclovir and gammaglobulin. Graft-versus-host disease: It is one of the major complications of allogeneic hematopoietic stem cell transplantation due to different histocompatibility complex antigens between the donor and recipient, and the implanted immunologically active cells are sensitized by the recipient antigens and increase in value and differentiation to attack the recipient cells directly or indirectly. It is one of the major complications of allogeneic HSCT. It is classified as acute and chronic. Clinical manifestations: Skin papules with varying degrees of pruritus, mostly on the palms, soles, behind the ears, face, neck, trunk, and extremities. Oral buccal mucosa, lips, and palate may have mucosal white spots and ulcers, which may cause oral pain and cause difficulty in eating. The eyes may show keratoconjunctivitis, dry eyes, and foreign body rubbing sensation. The liver manifests as abnormal liver function. Intestinal manifestations are abdominal pain and diarrhea, dark green watery stools, nausea, vomiting, and loss of appetite. Prevention: 1. Wear clean and soft underwear, avoid rubbing the skin, pay attention to the color of the rash, the time of appearance, and the area; do not scratch the skin with your hands when the skin itches, keep the bed sheets clean, and change underwear regularly. 2. Keep the mouth clean. Observe whether the oral mucosa is oozing blood, ulcers, pain, dry lips; avoid spicy and stimulating, spiny and overheated food when oral graft-versus-host disease occurs. 3. Use artificial tears when eyes are dry. In case of keratitis, advise the patient to rest in bed, give eye shields and dim the light when photophobia and lacrimation occur. 4. Observe the nature of stool, the number of times of diarrhea and abdominal pain; accurately record the number, amount and color of diarrhea; rinse the perianal area with iodophor water after each stool to keep the perianal area clean. 5.Strengthen dietary management, give liquid food or fasting according to the severity of the disease, and accurately record the amount of in and out.