Objective To compare the diagnostic value of two-dimensional ultrasound and three-dimensional color Doppler ultrasonography combined with alpha-fetoprotein (AFP) and creatine kinase (CK) in the diagnosis of scar uterus and placenta previa implantation.Methods 120 cases of pregnancy delivery documented in our hospital from February 2013 to January 2017 were selected as the research object.All cases were divided into implantation group and non implantation group accorded to the pathological diagnosis.The implantation group of 44 cases were diagnosed as placenta previa implantation and the non implantation group of 76 cases were diagnosed as non placenta previa implantation.Two-dimensional ultrasound and three-dimensional color Doppler ultrasound diagnosis characteristic and effect in the two groups were recorded.The AFP,CK expression in the two groups were also detected.Results AFP and CK expression were detected in the serum levels of all pregnant women.The AFP and CK expression in the implantation group were (152.80 ± 11.66) μg/L and (125.98 ± 16.67) IU/L,significantly higher than non implantation group [(80.65 ± 22.84) μg/L and (77.55 ± 23.32) IU/L,P ＜ 0.05].Ultrasonic diagnosis of placenta implantation in 39 cases,arid non placenta previa implantation81 cases;there were 38 cases of placenta accreta and 82 cases of non placenta previa implantation judged by AFP and CK expression;43 cases of placenta previa implantatio,and 77 cases of non placenta previa implantation judged by ultrasound combined with AFP and CK.So the combined diagnostic sensitivity were significantly higher than that of single diagnostic sensitivity (P ＜ 0.05).The receiver operating characteristic (ROC) curve shows that the area under the curve of ultrasound is =0.879,AFP and CK =0.835,and the ultrasound was better than AFP and CK.Conclusions The two-dimensional ultrasound and three-dimensional color Doppler ultrasonography combined with AFP and CK in the diagnosis of scar uterus and placenta previa implantation can improve the diagnostic effect,and they have very good application values.