Objective To explore the application value of magnetic resonance imaging (MRI) and transabdominal color Doppler ultrasound in prenatal diagnosis of placental implantation abnormality (PIA). Methods 70 cases of pregnant women treated with MRI and ultrasound prenatal examination in our hospital from May 2015 to May 2017 were retrospectively analyzed. The imaging features of the two examinations were compared, and the diagnostic efficacy of MRI and transabdominal color Doppler ultrasound were analyzed, and the diagnosis sensitivity, specificity and accuracy of anterior and posterior uterine wall placental implantation were compared, and the typical imaging features of MRI in PIA and non PIA patients were analyzed. Results There was the abundant blood flow in the placenta muscle side, not enough layer continuity, the disappeared placenta peripheral space and the increasing placental vessels shown in the transabdominal color Doppler ultrasound. There were the uneven thickening placenta with irregular shape, uneven signal, increasing local blood vessels, unclear boundary with the uterus wall and low signal in T2WI shown in the MRI examination. The sensitivity, specificity, accuracy of MRI for PIA with 86.84%, 90.63% and 88.57% respectively were higher than those by transabdominal color Doppler ultrasound (P<0.05). The sensitivity and specificity of MRI in the diagnosis of posterior wall placental implantation were significantly higher than those of transabdominal color Doppler ultrasound (P<0.05). The incidence rates of placental vascularity, low placental T2 signal, and local expansion of uterus and other imaging signs in the PIA patients were significantly higher than those in the non PIA patients (P<0.05). Conclusion Compared with abdominal color Doppler ultrasound, MRI has a higher diagnostic value in PIA, and especially has obvious advantages in the posterior wall placental implantation diagnosis.