The scattering characteristics simulation of microsphere defects in sapphire wafers is implemented based on the generalized Lorenz-Mie theory, the influences of the receiving position of scattered light, defect size, the wavelength of incident light on the scattering light intensity are analyzed. The results show that the spatial scattering light intensity in the front scattering direction contains the largest amount of information, so the test results are the most accurate. The defect size has significant effect on the scattering light intensity distribution, therefore, it is possible that the characteristics of the scattering light intensity distribution curves can be used as the basis to estimate the defect size. The smaller the wavelength of the incident light, the more accurate the detection results.