Embodiments of the present invention relate to a bi-direction optical sub-assembly and an optical transceiver. A transmitter in the bi-direction optical sub-assembly is configured to transmit a first communication signal or a detection signal, where the first communication signal or the detection signal is input from a first end of a first optical path and output from a second end of the first optical path, enters a second end of a third optical path through reflection of a WDM optical filter, and is input from a first end of the third optical path to an optical fiber. A second communication signal received by the optical fiber is input from the first end of the third optical path and output from the second end of the third optical path, and the second signal is received by a BOSA receiver through transmission of the WDM optical filter.