The Talbot effect of the two-dimensional optical beam splitter fabricated by selective etching of MgO-doped LiNbO3 (MgLN) crystal is analysed based on the Fresnel diffraction theory. Numerical simulation is applied to study the intensity distribution of near-field optical diffraction under various duty cycle D and Talbot distance coefficient β. Based on the theoretical result, the selective etching optical beam splitter is designed and fabricated with various duty cycles. Through optical experiments, the fractional Talbot diffraction imaging map is obtained at different Talbot distances. The results obtained show that good near-field diffraction images can be achieved at D=52%, β=2, which verifies the results of the numerical simulation research.