〔Abstract〕 Objective To investigate the prenatal ultrasound diagnosis of abnormal invasive placenta by measuring the peak flow velocity of systolic blood flow under placenta. Methods A total of 133 pregnant women(≥28 weeks of gestation) who received placenta previa were enrolled, including complete placenta previa and anterior placenta with ≤2 cm distance between the placental edge and internal os. The US company VOLUSON E8 color Doppler ultrasound was used to examine the absence of the vocal cord area behind the placenta, the thickness of the posterior placental muscle layer<1 mm, the flow of the placental cavity ≥10 cm/s, and the peak systolic velocity(PSV). Ultrasound characteristics such as PSV were used to predict the accuracy of abnormal invasive placenta using receiver operating characteristic(ROC) curves. Results Compared with non-invasive placenta patients, the average gestational age of patients with invasive placenta decreased, the number of previous cesarean section increased, and PSV increased(P<0.05). There was no significant difference in the resistance index(RI) between patients with invasive placenta and non-invasive placenta(P>0.05). The area of PSV under the ROC curve predicting abnormal invasive placenta was 0.910(P<0.001, 95%CI: 0.873～0.962) while the area of RI under the ROC curve predicting abnormal invasive placenta was 0.562(P=0.336, 95%CI: 0.461～0.663). When the blood flow PSV under the placenta of the anterior wall of the uterus was ≥41 cm/s, the sensitivity of the abnormally invasive placenta was 89.47%, the specificity was 84.21%, the positive predictive value was 80.95%, and the negative predictive value was 91.43%. Conclusion The measurement of peak flow velocity during systolic blood flow in placenta may be a new marker for ultrasound diagnosis of abnormal invasive placenta, with high sensitivity and specificity.