根据折射率椭球方程，研究了光沿任意方向传播时铌酸锂晶体的横向电光效应，分析了不同传播方向下的感应折射率特性。沿y方向加电场时，除沿光轴方向传播外，当入射波矢在c-y平面或者c-x平面内时，感应折射率与所加电场呈线性变化关系，但线性特性和光轴方向相关；在其它传播方向上，感应折射率与所加电场以不同的非线性规律变化。沿x方向加电场的感应折射率特性和沿y方向加电场时的性质类似，但相同特性对应的传播方向绕c轴转动了45°。研究结果对铌酸锂晶体横向电光效应的拓展应用有实际意义。

Transversal electro-optic effect of light propagating in arbitrary direction in LiNbO3 is studied based on the index ellipsoid equation. The characteristics of inductive refractive index of crystal in different directions are investigated. When the electric field is applied along y axis, besides light propagating along the c axis, for the cases of light propagating in the c-y or c-x plane, the inductive refractive index is linearly proportional to the applied electric field and the linear curves are different in different propagation directions. In other cases, the inductive refractive index and the applied electric field have different curves of nonlinear variation in different directions. When the electric field is applied along x axis, the inductive refractive index has the similar characteristics. But the propagating directions holding linear relation are related to the c axis by a 45°rotation. The results will be helpful to the new applications of electro-optic effect of LiNbO3 crystal.