The present invention discloses a receiving apparatus, a sending apparatus, a system and a method for optical polarization division multiplexing. The receiving apparatus includes: an optical splitter, configured to: split a received polarization-multiplexed optical signal into two identical polarization-multiplexed optical signals, where the two polarization-multiplexed optical signals both include a first State Of Polarization (SOP) optical signal and a second SOP optical signal, and the first SOP optical signal is an optical signal when a horizontal-SOP optical signal is transmitted to the optical splitter, and the second SOP optical signal is an optical signal when a vertical-SOP optical signal is transmitted to the optical splitter; a horizontal optical signal obtaining apparatus, connected to the optical splitter and configured to separate the horizontal-SOP optical signal; and a vertical optical signal obtaining apparatus, connected to the optical splitter and configured to separate the vertical-SOP optical signal.