According to the need of ultrafast laser micro-processing technology,we propose a method utilizing electro-optic crystal′s beam deflection principle to generate dynamic precision micro-displacement.Four wedge-shaped electro-optic crystals make a special structure.Adjusting the voltages on the electro-optic crystals,the beam can produce a dynamic horizontal displacement.Adding rotation to this,the beam can be controlled to process inverse taper holes.This paper describes the method of generating lateral displacement,and analyzes the parameters that impact the greatest horizontal displacement.Taking KDP,D-KDP,RTP and other electro-optic crystals as examples,it is discussed the relationship between crystal lengths and the dynamic range of horizontal micro-displacement.With incident beam diameter of 3 mm,electro-optic crystal thickness of 3 mm,width of 30 mm,overall length of 210 mm,wedge angle α of 0.3 rad,RTP electro-optic crystal can produce 0~700 μm dynamic lateral displacement by adjusting the voltage from 0 to 90000 volt.