A power jack, comprising an insulating housing, a socket which set in the bottom of the insulating housing, a movable socket cover which covers the socket and an elastic device between the socket cover and the socket which for ejecting the cover; the housing has a pair of limiting portions each having a button assembled thereto; the socket cover has an elastic arm which could clamp the limiting portion, so as to lock the socket cover; the elastic arm can be pushed away from the limiting portion by the button, so that the cover can be removed away from the socket. Therefore, it is convenient and safe for users to extract the plug with single hand.