The present disclosure discloses an electrical connector including an insulating body, a number of conductive terminals and a shielding shell. The insulating body includes a mating surface and a slot. Each conductive terminal includes a contact portion extending into the slot. A receiving groove for receiving a part of a mating connector is formed between the shielding shell and the insulating body. The receiving groove is located outside the slot. The electrical connector further includes a first outer surface and a fool-proof protrusion protruding beyond the first outer surface in a direction perpendicular to an insertion direction of the mating connector. The first outer surface and the receiving groove are located on two opposite sides of the slot, respectively. The fool-proof protrusion is adapted to prevent the mating connector from being inserted into the electrical connector at a wrong angle.