The present invention relates to a spring operating mechanism and an opening latch assembly thereof. The spring operating mechanism comprises the opening latch assembly, wherein the opening latch assembly comprises an output shaft crank arm that is arranged on a corresponding output shaft. The opening latch assembly further comprises an opening latch that works with the output shaft crank arm to limit an opening spring in a charged state and a return spring that is connected to the opening latch. The return spring is a compression spring. The return spring is in a compressed state, and no hook is formed on both ends of the return spring. Overall force on the return spring is relatively even, and the return spring is not liable to break.