Objective To study the value of ultrasound combined with 3.0MRI (magnetic resonance imaging) in the diagnosis of cesarean scar pregnancy after cesarean section. Methods 200 patients with suspected cesarean scar pregnancy after cesarean section admitted in our hospital between January 2011 and January 2016 were selected as study subjects. All patients underwent ultrasonography before operation, and suspicious patients underwent MRI after ultrasonography. With surgical and pathological results as the golden standard, the diagnostic sensitivity, specificity, positive predictive value, negative predictive value and accuracy of ultrasound combined with 3.0MRI were calculated. Results The sensitivity, specificity, accuracy and Kappa value of ultrasound combined with MRI were 98.7%, 94.2%, 97.5% and 0.93, respectively.The specificity and accuracy of combined examination were significantly higher than those of ultrasound (71.2%, 89.5%) (P<0.05). Conclusion Ultrasound combined with 3.0MRI can improve the accuracy in the diagnosis of cesarean scar pregnancy after cesarean section, and provide reliable imaging evidence for the choice of treatment plan.