An electrical receptacle connector includes an inner shell, a terminal module in the inner shell, and an outer shell out of the inner shell. Two side plates, a top plate, and a bottom plate of the inner shell are connected with each other to form an insertion opening, and the insertion opening is near one end of the inner shell. The outer shell is out of the inner shell and near the insertion opening of the inner shell. The outer shell stacks on the two side plates, the top plate, and the bottom plate of the inner shell to form a double-layer shell structure. Accordingly, the structural strength around the insertion opening of the inner shell can be improved. Hence, when a plug connector is inserted into the insertion opening of the inner shell, the inner shell does not deform or bend easily.