Abstract: In the present study, the weight lose rates, cell membrane permeability, malondialdehyde（MDA） contents,superoxide dismutase（SOD）, peroxidase（POD）, catalase（CAT） activities and texture characteristics of passion fruits after melatonin（200 μmol/L） and water soaking treatments were analyzed during the storage（4 ℃）, aiming to investigate the effects of melatonin treatment on the physiological and structural characteristics of postharvest passion fruits. Results showed that melatonin treatment could effectively reduce the water loss, delay the increase of weight loss rates, maintain the higher levels of SOD and CAT activities, and inhibit the POD activity and MDA accumulation, reduce the cell membrane permeability, keep the integrity of cell membrane of passion fruits during storage, finally leading to maintain good texture and quality of postharvest fruits, and delay the senescence.