Abstract: OBJECTIVE To explore the actual effect of mycoplasma infection on perinatal outcome in late trimester of pregnancy, so as to provide reference for pregnancy check study and practice. METHODS A total of 634 cases of pregnant women in late trimester of pregnancy from Nov. 2013 to Oct. 2014 were chosen as the research objects. Based on mycoplasma culture results, they were grouped into the positive group and the negative group, 153 cases and 481 cases respectively. The complications for the two groups of pregnant women and newborns were observed and compared, using SPSS 19.0 to analysis. RESULTS In positive group newborns, the positive mycoplasma was in 68 cases, and the positive rate was 44.44%. In the negative group of 481 cases of newborns, positive mycoplasma was in 6 cases, and the positive rate was 1.25%. The rates of perinatal premature rupture of membranes, fetal distress, premature delivery and puerperal disease occurrence for the positive group of pregnant women were 43.14%, 21.57%, 15.69%, 11.11%, which were higher than the negative group (P＜0.05). CONCLUSION Mycoplasma infection can cause the increasing of complications in late trimester of pregnancy for pregnant women and their fetuses. Early screening of mycoplasma infection for pregnant women may have great clinical significance in prevention of adverse perinatal outcomes.