Based on the birefringence of the LiNbO3 (LN) crystal, it firstly designed a electro-optic Q-switching technique with a pre-deflection of LN crystal. This technique can optimize the structure of Q-switched laser oscillators. Then it analyzed the angle of the pre-deflection the LiNbO3 (LN) in theoretical and simulated the relationship between the angle and the length of the crystal. Finally, an experiment was done to confirm the design, and it successfully obtained the pulsed laser, whose pulse width was 15.76ns with a 108mJ energy.