In the thermal design of Embedded Power Chip Microwave Modules, the placement of chips on substrate has a significant effect on internal temperature field, thus, influence the reliability of the modules. In this paper, Based on BP-GA, the optimization for chips placement of EPCM is achieved by corresponding optimization program. To demonstrate the effectiveness of the results, ANSYS, finite element analysis (FEA) is carried out to assess the thermal field distribution of the optimization for chips placement. The result shows that the thermal field distributions of the optimization are consistent with the FEA results. The internal highest temperature of the initial placements is 90.369°C. After optimization, the internal highest temperature is 86.128°C, the highest temperature be reduced more than 5°C. It can effectively deal with the problem about optimize the thermal placement of EPCM chips, and improves the internal thermal distribution.