Apple fruits of the ‘cv. Starkrimson’ were artificially wounded, dipped with sodium nitroprusside (SNP) as an exogenous donor of NO at 0.5 mmol/L for 5 minutes. To investigate the weight loss and disease index of apple fruits during healing by SNP treated, we analyzed the activities of key enzymes and content of products in phenylpropanoid metabolism, H₂O₂ content and peroxidase activity at wound sites, and explored its relevant physiological mechanism, so as to provide a method and theoretical basis for rapid postharvest healing of apple fruits. The results indicated that: (1) SNP treatment effectively reduced the weight loss and disease index of inoculated fruits with Penicillium expansum during healing, which were 40.2% and 31.4% lower than the control at the 5th day after healing. (2) The treatment significantly increased the activities of phenylalanine ammonia lyase, cinnamic acid4hydroxylase and cinnamyl alcohol dehydrogenase, the key enzymes of phenylpropanoid metabolism, and enhanced the contents of cinnamic acid, coffeic acid, ferulic acid, sinapic acid, total phenols, flavonoids, Pcoumaroyl alcohol, coniferyl alcohol, sinapyl alcohol and lignin at wound sites of fruits. SNP treatment also significantly raised H₂O₂ content and POD activity at wound sites of fruits. It was found that NO could promote the wound healing of apples by activating phenylpropanoid pathway, increasing H₂O₂ content and POD activity at wound sites.