The invention discloses a power transmission device with a clutch mechanism, comprising a transmission shaft, clutch wheels, cover caps, check rings and separators, wherein connecting parts are arranged at one ends of the clutch wheels and installation parts are arranged at the other ends of the clutch wheels; a convex ring-shaped connecting part is arranged on the peripheral wall of the transmission shaft, the connecting parts of the clutch wheels are sheathed on the ring-shaped connecting part, multiple unidirectional clutch grooves formed in circumferential direction at equal distances are arranged in center holes of the connecting parts of the clutch wheels, one end of the ring-shaped connecting part of the transmission shaft, away from the clutch wheels, is provided with a ring-shaped notch, each separator comprises a ring-shaped fixing part, and a ring-shaped separating boss which protrudes outwards from the peripheral wall of the fixing part and is used for separating each unidirectional clutch groove into two containing cavities, and a roller and a flat spring for providing reset elastic force to the roller are arranged in each containing cavity. According to the power transmission device, the working reliability is effectively improved and the service life can be prolonged.