In the process of using the fast steering mirror (FSM) which corrects the laser beam, the residual beam irradiates the FSM base structure and causes deformation, which may have adverse effects on the system, a targeted research has been carried out on the design of FSM base structure. The material selection and structure layout of the FSM base structure is analyzed in detail, and the aluminum base structure is chosen. The hollow-carved design method is adopted in the densest beam in the middle of the base, and the design direction of SiC material base is proposed. Thermal analysis and calculation are performed to the hollow-carved FSM base structure, the feasibility of the design method is verified and a new design idea for the structure design of similar FSM base structure is provided.