The invention belongs to the field of alternating-flow hydraulic technologies, and provides a three-phase alternating-flow hydraulic motor. For a bidirectional rack cylinder A, a bidirectional rack cylinder B and a bidirectional rack cylinder C in the three-phase alternating-flow hydraulic motor, an alternating flow is preset, the bidirectional rack cylinder A meshes with a gear A, the bidirectional rack cylinder B meshes with a gear B, and the bidirectional rack cylinder C meshes with a gear C, so that a motor shaft is driven to rotate; for the gear A, the gear B and the gear C, each gear canindependently act on the motor shaft through a corresponding one-way needle roller clutch so that the motor shaft can rotate continuously; and the installation angles of the one-way needle roller clutches on the motor shaft are adjusted so that the rotating direction of the motor shaft can be changed. According to the three-phase alternating-flow hydraulic motor, the structure is ingenious, the layout is reasonable, one-way continuous rotation of the hydraulic motor can be realized in the alternating-flow hydraulic pressure, and good popularization value is achieved.