Aiming at the problems of low contrast of the optical lens image and low recognition rate of optical lens surface defects under single illumination when detecting optical lens surface defects by machine vision, a visual detection method of optical lens surface defects under dual light sources is proposed. According to the scattering imaging principle, the optical lens images containing defects are obtained by using the image sensor under two different illumination modes, the forward light and the backlight, and then the images are fused into one image by the image fusion algorithm. Finally, the defect size information of optical lens surface is obtained by using the recognition algorithm. Two different defects (scratch, pitting) are detected, and the test results of this system are compared with the processing results of the ZYGO interferometer, and the comparative results show that the pitting error and the scratch error of proposed method are less than 2.7% and 0.8%, respectively, the detection efficiency is inproved by 98.24% compared with the interferometer, and the detection time is shortened. Compared with the detection method under single illumination and manual detection, the identification rate and accuracy of defects detected by the proposed method is higher.