A novel mixed flexible support structure was proposed to satisfy the requirements of surface and position accuracy of a large-aperture lens. First, Castigliano’s second theorem was used to analyze the various flexible hinges and the whole flexibility model of the support component was established. Then, the objective function of the total deformation energy of the flexible support assembly was used to establish the constraint equation based on the position accuracy and the actual space requirements, and a structural optimization design model was established. It was determined that the radially flexible support structure was the most sensitive to the flexibility of the flexible support assembly, and its stiffness was verified. Finally, the finite element analysis of the optimized whole structure of the lens assembly was carried out, and the surface accuracy was obtained by using the geometric fitting method. The simulation results show that the surface shape accuracy of the new hybrid flexible support structure is better than λ/20 (λ=632.8 nm) under various conditions. The novel mixed flexible support structure and its theoretical analysis process can provide a reference for the supporting technology of high precision large-aperture lens.