The invention discloses a single-fiber bidirectional BOSA structure. The single-fiber bidirectional BOSA structure comprises a packaging housing, a TOSA, an ROSA, and a light transmit-receive integrated optical structure. The TOSA comprises a light emitting group and a wavelength division multiplexing structure, and the ROSA comprises a light receiving group and a wavelength division de-multiplexing structure; one end of the housing is provided with an optical interface, and optical signals received by the optical interface are emitted to the wavelength division de-multiplexing structure of the ROSA through the light transmit-receive integrated optical structure; signal light emitted by the TOSA, after light combination through the wavelength division multiplexing structure, is transmitted to the optical interface through the light transmit-receive integrated optical structure, and the optical interface outputs the signal light emitted by the TOSA; and the TOSA, the ROSA and the light transmit-receive integrated optical structure are packaged in the housing. According to the invention, the structure is used for a four-channel high-speed transmit-receive system, uplink and downlink transmission is carried out directly on one fiber, external devices or equipment is unnecessary, the system structure is greatly simplified, the operation cost is decreased, the assembling is convenient, the insertion loss is effectively reduced, the coupling efficiency is enhanced, the temperature performance is good, and long-distance transmission of the optical signals is facilitated.