In order to meet the application requirements of pimi-level stability and λ/30 wavefront error in space gravitational wave detection, an optical and mechanical integrated analysis and optimization method is proposed. Firstly, the position analysis of the support points on the main mirror side and the topology optimization of the support structure were carried out. Then, based on the flexibility matrix of parallel Bipod linkage support, the evaluation function of each structure parameter is established, and the value range of flexible support size parameters was preliminarily determined by Matlab analysis. Finally, an integrated optical and mechanical simulation platform was built to further optimize the structure.The results show that the first-order frequency of the system is 392.23 Hz, and the deformation of the primary mirror surface deformation under gravity and temperature loads is better than λ/60. Under thermal disturbances in a space environment of 10 μK/Hz^1/2, the dimensional stability of the primary mirror component is at a level of 10 pm/Hz^1/2.