An air pump includes a connector connecting to an air nozzle of an object to be inflated, a holder block connected to the connector and having a valve chamber, an air cylinder air inlet and a manual charge air inlet extended from the vale chamber to the rear side thereof, and an air passage extended from the valve chamber to the inside of the connector, a press button mounted in the holder block and movable between a first position and a second position, a fixed cylinder connected to the holder block and holding an air cylinder, and a movable cylinder sleeved onto the fixed cylinder for reciprocating to pump air into the fixed air cylinder.