The invention discloses a closing drive device of a circuit breaker. The closing drive device comprises a handle mechanism, a slider-crank mechanism and a motor, wherein the handle mechanism is provided with a drive part; the motor is used for driving the handle mechanism to perform closing operation through the slider-crank mechanism; an operation space is reserved between the slider-crank mechanism and the handle mechanism and is sufficient for manual opening or closing operation performed by the handle mechanism. The closing drive device and the circuit breaker using the device are simple in structure, low in manufacturing cost and small in volume, and the closing drive device is suitable for small-sized circuit breakers. Moreover, a manual closing/opening function is further provided while an automatic closing/opening function is provided.