The invention discloses a closing keeping device for a spring operation mechanism. The device comprises an output crank which is connected with the fracture of a breaker by a connecting board and driven by a cam system, and an opening and closing trigger which is fixed on a mechanism frame. The device is characterized in that the output crank is provided with a closing keeping lock pin which is blocked by a closing keeping interlock mechanism that is arranged between the output crank and the opening trigger after the closing is finished, thus keeping the closing operation in steady self-lock state. The device can keep the breaker in the closing position reliably and steadily.