An AC contactor with a mechanical short circuit self-locking function includes an AC contactor body. The AC contactor body includes a shell body, wherein a mechanical short circuit self-locking unit is provided therein. The mechanical short circuit self-locking unit includes a short circuit detecting and triggering device for generating a triggering action when a fault of short circuit occurs; and a self-locking acting device for generating a self-locking action after receiving the triggering action, so as to disable the AC contactor to automatically reset after the fault of short circuit is removed.