Abstract: Objective: To investigate the causes and influencing factors of spontaneous abortion for providing the basis in formulating the control measures,guiding prepotency and maternal and child health care.Methods: Four hundred and eight patients with spontaneous abortion and 461 puerperas with normal pregnancy and labor were divided into the case group and control group according to the case-control study.The risk factors in two groups were investigated and analyzed.Results: One way ANOVA analysis showed that the age,profession,vaginal bleeding during pregnancy,family history of early pregnancy,pregnancy complications,folic acid application,pregnancy times and history of abnormal pregnancy were the influencing factors of spontaneous abortion(P<0.01).Multivariable logistic regression analysis showed that the age,clothing profession,chemical profession,beauty salon profession,building decoration profession,vaginal bleeding during pregnancy,family history of early pregnancy,folic acid use,reproductive tract infection,viral influenza,pregnancy times and history of abnormal pregnancy were the independent factor of spontaneous abortion.Conclusions: The age,clothing profession,chemical profession,beauty salon profession,building decoration profession,vaginal bleeding during pregnancy,family history of early pregnancy,infection during pregnancy,pregnancy times and history of abnormal pregnancy are the independent factors of spontaneous abortion,and the folic acid is a protective factor of spontaneous abortion.