In order to determine the physiolosical characteristics of plum fruits(Oishi wase) during maturation and guilty according to temperature after harvest, (2-chloroethyl) phosphonic acid(ethphon) 390ppm was sprayed on plum tree 11days before commercial matuarity in Suwon area. And also this study was acted to investigate fruits quility(Formosa) influenced by temperature(room, low) and polyethylene films(0.03, 0.06, 0.1mm), 1. Effect of ethphon on the fruits maturation and fruits(Oishi wase) quility according to temperature ofter harvest. Ethephon stimulated fruits ripening but the firmness was reduced rapidly. Soluble solids and titratable acidity was not very different than each treatment. Carbon dioxide and ethylene production were advanced and the production peak were shown earlier by ethephon treatment as compared with control fruit. Anthocyanin development was enhansed rapidly by ethephon treatment but it exerted a bad influence on fruits color after harvest, The soluble sugars in fluits were mainly glucose, sucrose, and fructose. Those content were higher in treated fruit than control. The organic acid was mainly malic acid. The shelf life was less than about 5days at room temperature and about 10 days at low temperature. 2. Fruits(Formosa) quility as affected by polyethylene film bagging. The polyethylene films well maintained the firmness both room and low temperature. Low temperature was more effective in maintaining titratable acidity than room temperature, especially polyethylene films. On the Other hand, soluble solids content was not shown wide differance between room and low temperature. Polyethylene film showed a high resperation rate, the rate was higher at room temperature than low temperature and thicker films revealed higher rate. Otherwise, ethylene production was low in all treatment Polyethylene film inhibited the coloration of fruits, decreased anthocyanin content. Fruits coloration delayed by low temperature in control. The shelf life of plum fruits was about 6 days at room temperature and 13 days at low temperature in control Polyethylene film had no advantage on shelf life both at room and low temperature.