Objective To analyze the risk factors of placenta previa with placenta accreta and the diagnostic value of prenatal MRI on placenta previa with placenta accreta. Methods The clinical data of 96 patients with placenta previa and placenta accreta (study group) and 128 patients with placenta previa but without placenta accreta (control group) from January 2016 to January 2017 were analyzed retrospectively, among which 130 patients with suspected placenta accreta were given preoperative MRI. Logistic regression analysis was used to analyze the independent risk factors affecting placenta previa with placenta accreta. The diagnostic values of MRI in placenta previa with placenta accreta and implant classification were observed. Results There were significant differences in the data of pregnancy way, gravidity, parity, abortion frequency, cesarean section frequency and history of uterine surgery between the two groups (P<0.05). Logistic regression analysis showed that abortion frequency≥ 2 times, cesarean section frequency ≥ 1 time and history of uterine surgery were independent risk factors for placenta previa with placenta accreta (P<0.05). The sensitivity, specificity, accuracy, positive predictive value and negative predictive value of MRI in the diagnosis of placenta previa with placenta accreta were 81.25%, 94.12%, 84.62%, 97.50% and 64.00% respectively, and the coincidence rate with pathological diagnosis of implant classification of placenta previa with placental accreta was 73.08%. Conclusion MRI has a good diagnostic effects on placenta previa with placenta accreta. Patients with abortion frequency ≥ 2 times, cesarean section frequency ≥ 1 time and history of uterine surgery and other factors affecting the risk factors of placenta previa with placenta accreta should be taken seriously and given timely MRI and other examinations.