Abstract: Mud crab, Scylla serrata , is an economic crustacean living in estuarine waters. Studies on mechanism of low temperature adaptation are important for low temperature breeding,as well as crab aquiculture. Two-division electrophoresis, including isoelec-trophoresis focusing (IEF) and sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) ,was important method for proteins division in proteomes, which was used to determine expression of specific proteins in hepatopancreas of Scylla serrata under low temperature acclimation. In addition, gas chromatography was used to determine fatty acid composition in different low temperature acclimation groups. Scylla serrata , were enforced to experience 3 weeks acclimation under different low temperature, hepatopancreas of whom was taken out from each crab respectively. Hepatopancreas from ten crabs of each group was mixed to perform experiment. The experiment results showed that there were 22 difference proteins in hepatopancreas between 5 ℃ acclimation group and 27℃ group. 15 proteins were expressed in 5℃ acclimation group and without in 27℃ group .there were 7 proteins in 27℃ group and without in 5℃ acclimation group, there were 18 difference proteins between 10℃ acclimation group and 27℃ group,namely that, 14 specific proteins were expressed in 10℃ acclimation group,and 4 in 21℃ group;there were 6 specific difference proteins between 15℃ acclimation group and 27℃ group, 5 specific proteins were expressed in 15℃ acclimation group and without in 27℃ group,one protein appeared in 27℃ group and without in 15℃ acclimation group. For matches of difference proteins in different acclimation groups, 14 proteins were matched in 5℃ and 10℃ group, while specific difference proteins in 15℃ group were not matched with 5℃ and 10℃ at all. these results indicated that specific proteins expressed in 5℃ and 10℃ were almost corresponding, while those expressed in 15℃ group is resmble with 27℃ group. It is obvious that difference proteins between acclimation group and 27℃ group increased with acclimation temperature decrease. After acclimation of 3 weeks, the sum of the saturated fatty acids (∑SFA)in hepatopancreas in 5℃ and 10℃ acclimation groups were significantly lower than that in 27℃ group (PPPP<0.01)under low temperature acclimation. During the process of low temperature acclimation, changes in protein expression are dynamic. The lower acclimation temperature it is,the more specific difference proteins are expressed, the saturated index of fatty acid (∑SFA/∑UFA) decreases under low temperature acclimation. Changes of protein expression and fatty acid composition in low temperature are used to adapt to environmental changes and to maintain the physiological function of the hepatopancreas.