An electrical connector is provided for a mating connector to be inserted thereto. The electrical connector includes an insulating body having a tongue, and multiple terminals. A middle grounding sheet is located between the terminals in upper and lower rows, and has at least one first through hole. Each of left and right sides of the middle grounding sheet has a latch slot and a notch. The insulating body has a first insulating post entering the first through hole and a second insulating post entering the notch. A dimension of the second insulating post is larger than a dimension of the first insulating post. A metal shell frames outside the insulating body to form an insertion space. A first clearance between a first protruding portion and a shielding casing of the mating connector is more than or equal to 0.001 mm and less than or equal to 0.0449 mm.