The large-aperture bionic compound eye optical system can have a large field of view, it overcomes the defects that the aperture of biological compound eyes is small while the vision distance is short. The relationship between the actual array period and theoretical calculated period number was researched through analyzing the field stitching method of bionic compound eye, the method called "padding sub eye method" was proposed to reduce sub eye configuration density. By studying the geometry relationship of the fixed spherical body design, the mathematical connection between the main body vertical radius d and the curvature R was established, the design method of fixed spherical body was proposed, and the proposed bionic compound eye field stitching theory was perfected. Finally, the correctness of the design method through the actual alignment experiments was verified. This method can improve the integration of the bionic compound eye system, reduce system size, and promote the practical application of bionic compound eye optical system.