Objective To explore the clinical value of nuclear magnetic resonance (MRI) combined with ultrasound in the diagnosis of dangerous placenta previa. Methods The data of 97 patients with suspected dangerous placenta previa admitted to our hospital from April 2015 to February 2020 were retrospectively selected. The diagnostic value of three methods of ultrasound, MRI, ultrasound+MRI (parallel diagnosis) on patients were analyzed.Results Of all 97 pregnant women, 74 cases were diagnosed as dangerous placenta previa. The sensitivity data of the three diagnostic methods of ultrasound, MRI, ultrasound+MRI were statistically significant (P＜0.05). The combined sensitivity of ultrasound and MRI is higher than that of ultrasound or MRI alone. All pregnant women used the delivery method of cesarean section,40 cases were elective cesarean section, accounting for 41.24%, 57 cases were emergency cesarean section, 58.76%. 62 cases of the confirmed diagnosis were treated by percutaneous double uterine artery catheterization and embolization,accounting for 86.48%. Conclusion The diagnosis of dangerous placenta previa using ultrasound or MRI has ideal sensitivity, specificity and accuracy. When the two methods are used in combination, it can further improve the diagnosisefficiency, assist the physician to rationally arrange the surgical path, estimate the risk of surgery, and improve pregnancy outcome.