Research of the tunable two-dimensional hexagonal phase array grating based on periodically poled Mg-doped LiNbO3 (PPMgLN) crystal and its Talbot effect of light diffracton imaging is presented. Theoretical simulation is executed to study the intensity distribution of near-field optical diffraction under various phase differences and fractional Talbot distances. Average intensity of the sample area in diffraction field is simultaneously calculated with phase difference and fractional Talbot distance, so the position of the maximum intensity of the sampling area is located as the phase difference is constant or changing. On the basis of theoretical research, the tunable hexagonal phase array grating is designed and fabricated based on periodically poled Mg-doped LiNbO3 crystal. The Talbot diffraction imaging is successfully obtained, and the experimental results agree with the theoretical results well.