Abstract: To solve the heat dissipation problem of power battery, based on the theory of enhanced heat transfer in porous media, this paper innovatively proposed a phase change heat dissipation system of foamed copper gel and semiconductor thermoelectric coupling. The system is composed of open cell foamed copper filled with polyacrylamide hydrogel and semiconductor thermoelectric refrigeration sheet. The foamed copper hydrogel material is directly covered in the heating area of power battery, and the heat is dissipated by the evaporation of water in the hydrogel. On this basis, by comparing the natural cooling mode, the comprehensive research of experiment and numerical simulation is carried out. The research shows that the use of the composite cooling system can significantly reduce the maximum temperature of the battery. Under the optimal structural parameters, it is noted that with the increase of the input current of the thermoelectric cooler, the maximum temperature of the battery shows a parabolic trend of first decreasing and then increasing. The optimal current is 3A. NaCl solution can be used as the basic solution for hydrogel synthesis, which has better water absorption effect and promotes circulating heat dissipation. The results show that at the discharge rate of 1.5C, the corresponding maximum temperature is 36 ℃, which is 26 ℃ lower than that of natural cooling.