This study was performed to evaluate the diagnostic value of PET/MR for cancer screening in asymptomatic subjects. 1491 subjects in total were enrolled in this study. 33 cases were diagnosed with malignant tumors, whereas 17 cases were correctly detected by PET/MR and 16 cases were detected by other methods. The overall detection rate of PET/MR in asymptomatic subjects was 1.14%, and the sensitivity, specificity, positive predictive value, and negative predictive value of PET/MR were 51.52%, 99.66%, 77.27% and 98.91%, respectively. As a cancer screening method, FDG PET/MR has great potentials to detect various kinds of tumors and should be beneficial to combine with other screening modalities.