A small buttock may be caused by bad sitting posture, or may be caused by muscle atrophy, lipoma and other diseases, need to take general measures, medication, surgical treatment for the cause of the disease. 1. Bad sitting posture: if stilt legs for a long time, one side of the buttocks for a long time pressure, it is easy to cause a small buttocks, generally no special treatment, but need to correct the bad sitting posture, to a certain extent, can improve the asymmetry of the buttocks. 2. Muscle atrophy: when one side of the buttock muscle atrophy, there is a situation where the muscle volume becomes small, it will cause a small buttocks. Patients need to strengthen the hip muscle exercise, to ensure balanced intake of nutrients, if necessary, can follow the doctor’s instructions to apply nutritional muscle drugs, such as vitamin E, coenzyme Q and so on. For patients with inflammatory myopathy, glucocorticoids such as prednisolone and immunosuppressants such as cyclophosphamide and tacrolimus should be applied as prescribed by the doctor. 3. Lipoma: this disease can occur in any part of the fatty tissue, so when lipoma occurs in the buttocks, from the appearance of the buttocks can feel a large and small. If the tumor is large in size, you need to consider lipoma excision. To sum up, there are many reasons that lead to a small buttocks, you need to go to the hospital to see the doctor, to clarify the specific causes and then cooperate with the doctor to actively treat.