Objective This study analyzed the statistics of amniotic chorionic thickness (AMT) by ultrasound measurement to investigate the accuracy of AMT as a predictor of preterm labor. Methods In this study, a total of 100 pregnant women who were treated in our hospital were taken as the subject of this investigation. The thickness of the membrane was measured during 21-22 gestational weeks, 25-26 gestational weeks and gestational 30-34 weeks , respectively. The relationship among AMT, gestational age and preterm labor has been found by recording the results and tracking delivery time. Results The fetal membrane thickness of 100 pregnant women were measured in 21-22 weeks, 25-26 weeks and 30-34 weeks, respectively. The AMT of 100 pregnant women in these three stages were (1.17 ± 0.17), (1.29 ± 0.21) and (1.44±0.29) mm, which were statistically significant (P<0.05). Furthermore, the thickness of fetal membranes increased with the gestational age. There was significant difference between the ATM of the three stages (21-22, 25-26 and 30-34 weeks) in normal gestational age and that in the preterm birth (P< 0.05). All the difference was statistically significant. Conclusion It is confirmed that the thickness of fetal membranes by ultrasound measurement is simple and reproducible. The thickness of fetal membranes increases with the gestational age, and the occurrence of premature birth can be predicted according to the thickness of fetal membranes.