The exact expression about the intensity splitting ratio of double Wollaston prism is given based on reflection law, multiple-beam interference and Fresnel formula. The effect of the incident angle, the wavelength of incidence and the cut angle on the splitting ratio is given by Matlab software simulation, which results in the fact that the influence of incident angle, wavelength and cut angle on the intensity splitting ratio is negligible for glue spaced prism, and tremendous for air spaced types. The intensity splitting ratio varies periodically with these parameters for both types prism.