In this paper, theoretical researches on the MgO:LN tunable hexagonal phase array grating based on the Talbot effect were presented. Researches revealed the effects on the intensity distribution of near-field diffraction from array grating duty cycle which is defined as D, phase difference which is defined as Δφ and the distance coefficient which is defined as β. The results obtained show that good near-field diffraction images can be achieved at D=52%, Δφ=0.75π, β=0.2. Based on the theoretical researches, the tunable hexagonal phase array grating is designed and fabricated from periodically poled MgO:LN crystal. Through experimental test, the Talbot effect diffraction imaging map is successfully obtained at different Δφ and β, which verifies the results of the theoretical researches.