The invention relates to the field of pre-charge pneumatic guns, in particular to a pre-charge pneumatic gun with a self-inflating function. The pre-charge pneumatic gun comprises a gun body and an inflator pump, the gun body is provided with an air storage cylinder for air prestorage, the air storage cylinder comprises an air inlet end and an air outlet end, and the air outlet end is connected with a trigger component of the pneumatic gun. The inflator pump comprises a moving sleeve, a fixed sleeve and an inflating fixing head, the inflating fixing head is arranged at one end, away from the moving sleeve, of the fixed sleeve, and the fixed sleeve is arranged at the air inlet end of the air storage cylinder through the charging fixing head. An air valve connection block is arranged in theair inlet end and connected with a single-direction inflating connector, a screw knob and an inflating port of the inflating fixing head. The moving sleeve is provided with supports which are connectedly hinged to the moving sleeve.