A receptacle connector is adapted for receiving a plug connector which includes a casing and a plurality of plug terminals disposed in the casing. The receptacle connector includes a printed circuit board and a shell mounted on the printed circuit board. Portions of a front edge of the printed circuit board are recessed inward to form two fixing grooves with a tongue formed therebetween. A plurality of golden fingers are formed on two opposite surfaces of the tongue. The shell has a top plate, a bottom plate opposite to the top plate and two side plates connecting the top plate to the bottom plate. A space is formed among the top plate, the bottom plate and the side plates and receives the tongue. The side plates are restricted in the fixing grooves. The plug connector is inserted into the space with the plug terminals electrically abutting against the golden fingers.