A receptacle connector includes a body and a cover assembled outside the body. The body defines a receiving space and a pair of beams. The end of each beam stretches backward to form a guiding projection. The bottom of the guiding projection is a cambered surface. The cover is bent downward from the front portion to form a pair of elastic arms. The bottom portion of the elastic arm is bent forward to form a finger portion. While a plug connector is inserted into the receiving space of the receptacle connector, the elastic arms press against the pressing portion of the plug connector. When the plug connector is dragged accidentally, the elastic portion of the plug connector slides downward along the finger portion to the cambered surface of the guiding projections, and then slides out of the receiving space to set the plug and receptacle connector apart.