Abstract: In order to realize the 109 times absorption for residual laser after 4% sampling, a kind of design method of light absorber was given. From light entrance to light exit the absorber, total angle relations were derived, including the angle of entrance light intersection with the absorber, turnover angle from entrance to exit, the angle of exit light intersection with the absorber, and turnover angle of the light departure from the absorber. The calculated angles were taken into polarization formula, and the sampling efficiency from every intersection was gotten, and so the total process attenuation was obtained from light entrance to light exit the absorber. According to the above formulas, a kind of absorber was designed, and it was analyzed in optical software. The results show that the absorption can reach to 1011, which satisfies the absorption requirements and is identical with theory calculation; This kind of absorber has been used in the laser system well, near field image with modulation M1.2 and contrast C0.07 are gotten, so the design method is reasonable.