Even though plum is well known as a health food, the available processed food of it is quite limited. Furthermore it is difficult to find an easy processing method for leading to a value added product at farmhouse. This study was investigated to effects of temperature for plum extract juice by osmosis of yellow sugar. The plum was mixed with yellow sugar at equal ratio(w/w) to obtain yellowish extracted plum juice and then located in incubator at 15, 25, 35$^{circ}C$, respectively. The sugar content of extract was high at the early period but decreased throughout extraction period and it was about 66.1~67.4$^{circ}$Brix. The color difference was increased yellowish throughout the extract period. The pH of it was decreased throughout extract processing but citric acid content was increased. The speed of extraction during extraction processing was more rapid at 15$^{circ}C$ than 3$0^{circ}C$. However sensory evaluation score of taste and flavour was obtained at 15$^{circ}C$ than 3$0^{circ}C$, so the prefer temperature for plum extract juice by osmosis of yellowish sugar was 15~2$0^{circ}C$