Abstract: Effects of nitric oxide treatment on postharvest Physiology of ‘Jia Shi'Muskmelon fruit were investigated in this study.Jiashi Muskmelon were treated with 40, 60, 80μL / L nitric oxide ( NO) fumigation 3h, then stored in cold storage ( 5 ± 0.5℃) and observed the treatment effect. Changes in these levels of weight- loss rate, firmness of friuts, soluble solids ( TSS) , titratable acid ( TA) , respiration rate and ethylene production, superoxide dismutase ( SOD) , peroxidase activity ( POD) , catalase ( CAT) were measured during storage, in order to screened NO appropriate concentration of Jiashi Muskmelon. The results showed that under the three different of NO concentrations, 60μL / L NO treatment could better maintain Jiashi Muskmelon fruits hardness, slow the rise in the rate of weight loss; inhibit the soluble solids, titratable acid content; suppress the respiration rate and ethylene production of fruit; reduce the content of MDA. The 60μL / L NO treatment was able to significantly induce SOD, POD, CAT activity increased, enhance the antioxidant capacity of fruits.