To analyze the value of the anterior cervical angle (ACA) combined with cervical length (CL) measured by ultrasound of the pregnant women during the third trimester of pregnancy for predicting their spontaneous preterm labor, and to provide reference for the clinical evaluation. Methods: 221 pregnant women with high risk premature delivery from March 2018 to December 2020 were collected retrospectively. According to the pregnancy outcomes, these women were divided into group A (42 cases with premature delivery) and group B (179 cases with term delivery). All of the women in the two groups had undergone ultrasonic measurement of ACA and CL. The differences of the values of ACA and CL of the women were compared between the two groups. The predictive effect of the values of ACA combined with CL of the women for spontaneous premature delivery was analyzed. Results: The value of CL (25.8±7.0mm) of the women in group A was significantly lower than that (32.4±10.6mm) of the women in group B, but the value of ACA (115.3±10.2)°of the women in group A was significantly higher than that (105.3±11.5)°of the women in group B (all P＜0.001). History of abortion and/or preterm birth during the third trimester of pregnancy, CL <25mm, and ACA >109°were the independent influential factors of the spontaneous preterm birth (P＜0.05). And age ≥35 years, the pregnant complications, and the history of cervical surgery were not the independent influential factors of the spontaneous preterm birth (P＞0.05). The CL value, the ACA value, and the CL value combined with the ACA value of the pregnant women had certain predictive efficacy for spontaneous preterm birth (P＜0.05). The AUC, the sensitivity, of the specificity of the combined of measurements of CL and ACA values for predicting the spontaneous preterm birth were 0.863, 69.1%, and 73.7%, which were the highest. Conclusion: The efficiency of ACA and CL measured by ultrasound of the pregnant women during the third trimester of pregnancy for predicting their spontaneous preterm labor is better. When CL <23.5mm and ACA >123.4°of the pregnant women, the risk of their preterm birth will increase significantly.