The present disclosure provides a polarization beam splitter, a backlight module and a liquid crystal display apparatus. The polarization beam splitter comprises a second prism group and a first prism group formed sequentially from a light incidence side to a light outgoing side and meshing with each other; and a polarization beam splitting layer arranged on a meshing surface of the first or second prism group and configured to allow a first polarized light in an incident light to be transmitted through the polarization beam splitting layer to exit from the light outgoing side while reflecting a second polarized light in the incident light back to the light incidence side, the second polarized light having a polarization direction perpendicular to that of the first polarized light.