Abstract: In order to explore the effects of different concentrations of Pythium oligandrum pretreatment on the storage quality, disease resistance and phenylpropanoid metabolism of plum fruits during storage and shelf life, Xinjiang 'France' plum was used as the test material in this experiment. The pre-harvest plum was sprayed with P.oligandrum diluent (750 times), and the water was sprayed as the control group (CK). It was stored at 4~6 ℃ and relative humidity of 80%~90%, and the samples were taken every 8 days. The results showed that the pre-harvest spraying of 750 times P. oligandrum preparation could significantly inhibit the decrease of fruit hardness, which was 32.2% higher than that of CK group (P<0.05). The weight loss rate was reduced by 37.3% compared with the CK group. Inhibit the respiration intensity of plum fruit, the treatment group accounted for 75.2% of the CK group. At the same time, pre-harvest spraying of P. oligandrum significantly increased the phenylalanine ammonia lyase (PAL) activity by 17.6% compared with the control group (P<0.05). The cinnamic acid-4-hydroxylase (C4H) was increased by 26.2% (P<0.05) compared with the control group, and the activity of 4-coumaroyl-CoA ligase (4CL) was also increased by 8.9%, while promoting the accumulation of total phenol, flavonoids and lignin content. In summary, the treatment of P. oligandrum can delay the postharvest deterioration of plum fruits: Maintain fruit quality characteristics, enhance disease resistance and prolong storage period. This experiment provides theoretical support and technical reference for the green preservation of plum fruits.