As the optical voltage transformer(OVT)based on linear electro-optic effect often uses the transverse modulation mode

the uniformity of the distribution of electric field in the crystals directly affects OVT's accuracy and stability. Experimental results show that when the angle and the position of the incident light offset

the inhomogeneity of the electric field causes integral voltage error in the optical path. In order to resolve this problem

a new method of attaching the medium to electro-optical crystal is put forward. And an OVT on 110 kV voltage grade is designed based on this method

in which the internal electric field for BGO crystals of additional medium is simulated and calculated with the finite element software Ansoft Maxwell. The results show that the method can improve the uniformity of the electric field. With an increase in the thickness of glass

the uniformity of electric field is improved and tends to be stable. To attach the medium to the electro-optic crystal when the light path has an offset of 0. 5°

the error can be improved from 0. 11% to 0. 04%

and for the offset of 0. 1 mm

the error can be reduced from 0. 3% to 0. 08%

an appreciable improvement on the electro-optic crystal edges aggregation effect.