A shielding housing structure of an electric connector includes an insulating body including a first terminal slot for insertion of a first terminal set, a second terminal slot for insertion of a second terminal set, a socket for insertion of a preset board; a shielding housing having an accommodation space assembled with a top side of the insulating body, and top holes and lateral holes formed thereon, and an insertion hole formed on upper edges of the lateral holes; and a movable cover having a top covering plate having top openings, and a side covering plate having lateral openings. The top covering plate is plugged into the insertion hole, and can be slid to a first position to form thermal convection ventilation holes on the shielding housing structure, or the top covering plate can be slid to a second position to form an enclosing status of the shielding housing.