The characteristics of the defects on the automotive brake master cylinder piston and the difficulties in visual imaging were analyzed. The tridimensional combination system of multiple light sources was designed, which was suitable for the surface defect detection of the piston. Soft light was designed to reduce the noise in the detection image. The mathematical model of light intensity loss in the process of light emissionreflectionimaging was established. The polarization filtering method was proposed and used on the vertical light source and the camera lens. By choosing the polarizing direction of polarizing film, the brightness of the area without defect and the width of the reflective band could be reduced, and the image contrast enhanced. The defects on the piston surface were systematically image captured with the new light source system. The random sampling experiment with 300 sample size shows that the vision inspection after the optimization of light sources has no leak detection. The false positive rate is not more than 2%. The research conclusions can be further applied into other surface defect visual inspection areas.