100%。The nuclear magnetic resonance(NMR) imaging was proposed to detect the subtle bruises on fruits. Chinese pears were selected as the experimental object. The nuclear magnetic resonance images of pears were acquired by horizontal scanning mode. Image processing, which included auto thresh segmentation, morphologic operation and boundary extraction was finished by Matlab software. At last the corner detection was used to determine whether the pear had subtle bruises. Experimental results showed that detecting subtle bruises on fruits with NMR technique was feasible. The accuracy of detection for subtle bruises and other pears was 92.1% and 100%, respectively.