When the principal dielectric axes of the anisotropic crystals and the axes built for describing the direction of incident lightwave are different,discussing about the electric field E of the refracted light wave becomes a complex problem. But it is important for some phenomena of nonlinear optics in biaxial crystals. After a plane wave propagating from an isotropic medium into an anisotropic crystal without any restriction on the orientation of the axes above, general expressions about the direction and amplitude of the refracted light wave’s electric field E are given. The result proves that E can be got by solving a quartic equation and using the boundary conditon of electromagnetic field. When the incident light wave takes some special direction or propagate into some symmetrical crystals, the E of the refracted light wave is perpendicular to the direction of the unit wave normal. That is a special case and also be discussed. The results can be used to discuss the distribution of energy between the two refracted light waves.