Objective  To explore the causes,diagnosis and treatment of the spontaneous perforation of sigmoid colon (SPSC).Method  Retrospective analysis was made on the clinical data of 15 patients who had proved to be SPSC by operation and pathological study.Results  All the 15 cases of SPSC were proved by operation,11 of which had a history of chronic constipation.In this group,the preoperative misdiagnosis rate was 67%.Simple neoplasty was done for 4 cases,mend and sigmoidostomy for 7 cases,and resection and intestinal anastomosis plus transverse colostomy for 4 cases.12 out of 15 cases recovered,and the cure rate was 80%.Conclusions  SPSC is rare in clinic.This disease is always discovered in senior people,accompanied with a history of chronic constipation.Anatomic agent is one of the important causes.There is no specific clinical manifestation in this disease,therefore, the key to diagnosis is a full knowledge of the disease before operation.The main treatment is surgical procedures.