The mathematical model of fundus imaging under the non-coaxial array illumination is established. A micro optical system of fundus camera is proposed by using the independent design method of illumination light path and imaging light path, which avoids the interference of human cornea and omental objective reflected light on the retina image in the traditional fundus camera. The design of 6-array ring light source illumination system is completed, which is only 17.9 mm in length and the effective illumination line field of fundus retina is not less than 12 mm. The secondary imaging design is adopted in the imaging optical system.The modulation transfer function is better than 0.2@91 lp/mm and the distortion is less than 5% with 75 mm length. The simulation and design results show that the optical system of the proposed fundus camera can effectively suppress the stray light in the optical path which is conducive to obtaining high contrast retinal image. The results can provide a design reference for the development of high image quality, miniaturization and low stray light fundus camera.