Abstract: A wave-driven power generation device of converting gravity work is illustrated, which has two power generation modules, a pulley module and two transmission mechanism structures. The pulley module has a rail and a counterweight part, wherein the counterweight part moves back and forth along the rail in a first direction or a second direction due to wave fluctuation, and the first direction and the second direction are two opposite directions. The transmission mechanism structure has a driving part and a gear module rotating with the driving part, wherein the driving part moves along the first direction or the second direction accompanying with movement of the counterweight part, the gear module rotates with the shaft of the rotator set, and the shaft of the rotator set is kept to rotate in respect to a rotating direction to continue to generate the electrical energy due to transmission of the gear module.