Abstract: Objective To compare the diagnostic efficacy of PET/MRI versus contrast-enhanced MDCT in preoperative staging of gastric cancer. Methods From January 2017 to January 2019,PET/MRI was performed to 26 patients with gastric cancer in our center.Another 52 gastic cancer patients underwent contrast-enhanced MDCT were propensity-matched in a 1∶2 ratio.The PET/MRI and contrast-enhanced MDCT images were interpreted respectively for the preoperative staging.Then the diagnostic value of these two methods were compared according to the pathological gold standard. Results The sensitivity for T1,T2,T3-4 stage in PET/MRI was 100%,50% and 94%,which was higher than 70%,12% and 91% in contrast-enhanced MDCT.For accuracy,it was 100%,88% and 88% for T1,T2,T3-4 stage in PET/MRI,which was also higher than that in contrast-enhanced MDCT (81%,62% and 81%).PET/MRI was superior to contrast-enhanced MDCT in the specificity for diagnosis of both N0 and greater curvature positive lymph nodes,with 93% and 88% in PET/MRI,versus 65% and 47% in MDCT (P<0.05). Conclusion PET/MRI is superior to contrast-enhanced MDCT in diagnosis of preoperative staging of gastric cancer.