The invention discloses a double-inlet beam splitter enabling any beam splitting ratios. With the double-inlet beam splitter adopted, it can be ensured that the optical paths of split H light and V light are exactly equal, and therefore, the coherence of incident light can be ensured; since the separate H light and V light pass through similar paths and the identical reflectors, excellent stability can be ensured; with half wave plates adopted, the polarization of the light can be controlled, and therefore, control on the beam splitting ratios can be realized; beam splitting and combination unrelated polarization can be realized, or beam splitting and combination related to a certain proportion of polarization can be realized.