An electrical connector assembly (600) comprising a shielding housing (20) and a socket (40), and a buckle (60) assembled to the shielding housing. The shielding housing has a horizontal passage (22) and an entrance (220) backwardly communicating the passage and forwardly opening for receiving a plug (80). The socket is used for mating with a front end of a plug inserted therein. The buckle has a front latch (62) movable between an open position where a plug inside the shielding housing is permitted to be pulled out and a closed position where the front latch blocks the entrance of the shielding housing so that a plug inside the shielding housing is blocked from being pulled out.