Abstract: In order to study the effect of Wollaston prism on the intensity of single-mode Gaussian beam,the transmitting o light and e light were studied respectively by analyzing interference in the prism cementing layer. For a given single-mode Gaussian beam merged with two polarizing modes,the transmission polarizing light intensity of o and e oscillates in period with the incident light angle at the interface of the cementing layer, the thickness of the cementing layer, and the refracting index of the transmitter in the cementing layer,and that the amplitude and frequency of the oscillation change with them too. But in general,the effect on the transmitted Gaussian beam is less than 0.65%. In practice,if the relative intensity is required larger than 0.65%, the effect of Wollaston prism on the transmitting characteristics of Gaussian beam can be neglected.