Abstract: In the present study, the effects of pre-harvest methyl jasmonate（MeJA） treatment on disease resistance and qualities of ‘Jinqiu’pear fruits were investigated aiming to prevent and control the postharvest ring rot disease. The results showed that pre-harvest MeJA treatment of 10 mmol/L could effectively inhibit the occurrence of postharvest ring rot and enlargement of lesion diameter of‘Jinqiu’pears. Compared with the control, the incidence rates and lesion diameters of pear fruits were decreased by 10 percentage points and 11.3 mm respectively after pre-harvest MeJA treatment and Botryosphaeria dothidea wound-inoculation on the 16 th day under room temperature（25±2） ℃. Besides, pre-harvest MeJA treatment could also improve disease resistance of ripe‘Jinqiu’pear fruits by increasing the activities of defense-ralated enzymes including chitinase（CHI）, β-1,3-glucoglyase（GLU）, phenylalanine deaminase（PAL）, peroxidase（POD）, polyphenol oxidase（PPO） and hydrogen peroxide（CAT）, reducing the production of malondialdehyde（MDA） and promoting the generation of total phenolic substances, finally achieving the purpose of preventing ring rot occurrence of ripe fruits. Moreover, pre-harvest MeJA treatment could delay the decline of vitamin C contents and the increase of weightless rates to improve storage qualities of pears.