In the experiments of Rayleigh laser guide star (LGS) for adaptive optics on altazimuth Coudé telescope, the technology of LGS launched and received in the common aperture using polarizing beam splitting scheme is researched. Based on the Jones matrix method and the reflect characteristic of coating film on mirror, the physical model of polarizing beam splitting in altazimuth Coudé telescope is built. The efficiency of beam splitting for launching and receiving is simulated with numerical method in computer and compared with experimental result. The result shows that the efficiency of polarized beam splitting is periodically varying with the azimuth or elevation of the telescope because of the phase difference between the s and p polarizing vector reflected by film on the mirrors. The factors of degrading the polarizing beam splitting efficiency are analyzed. And a technical scheme for keeping the efficiency from degrading with the azimuth or elevation varying of the telescope is presented.