Abstract: In this study,the effects of melatonin at different concentrations(0,50,150,250,350 and 450 μmol/L)on Fengtang plum(Prunus salicina)were determined by measuring respiration rate,weight loss,firmness,soluble solide content(SSC),titratable acid(TA),vitamin C(V_C),the activity of peroxidase(POD)and polyphenol oxidase(PPO),the content of malondialdehyde(MDA)and organoleptic evaluation of quality of the fruit during storage at room temperature of (23±2)℃. The results showed that appropriate concentration of melatonin(150~350 μmol/L)effectively reduced the respiration rate and weight loss rate of the fruit;delayed the fruit softening,kept higher SSC and TA,inhibited the degradation of V_C,maintained good organoleptic evaluation quality and flavor;at the same time,melatonin treatment improved the activity of POD,reduced the activity of PPO and the accumulation of MDA,thus inhibited the degree of membrane lipid peroxidation,and delayed the maturation and senescence of Fengtang plum. Among the above melatonin treatments,the fruits treated with 250 μmol/L melatonin showed the best effects.