Compression effect of angular width for polarizing beam splitter under tilted incidence is caclulated. The calculated result shows that the larger the tilted angle is, the more distinct the compression effect, difference of substrate refractive index has little influence on the compression effect. The conclusion is testfied by the designing of thin fim coatings ulteriorly. In practical use when the direction of incident light is kept invariable the compression effect of angular acceptance width can be realized by changing the shape of the PBS prism. The result has a great help to design polarizing beam splitter with a wide augluar acceptance and spectrum bandwidth in practice.