A single-fiber bidirectional optical transceiver subassembly, related to technology of optical communications, including an optical transmitting subassembly, an optical receiving subassembly and an optical splitting and filtering unit. The optical transmitting subassembly is coupled with an optical input port of the optical splitting and filtering unit. The optical receiving subassembly is coupled with an optical output port of the optical splitting and filtering unit. A bidirectional port of the optical splitting and filtering unit is coupled with a single-mode fiber. Each optical element in the optical transmitting subassembly, the optical receiving subassembly, and the optical splitting and filtering unit is a spatial optical element. Single-fiber bidirectional transmission is implemented with small channel spacing, by improving the optical splitting and filtering unit.