An electrical connector assembly includes an electrical plug connector and an electrical receptacle connector corresponding to the electrical plug connector. The electrical plug connector includes a plug insulated housing as well as plug terminals and buckling portions on the plug insulated housing. The electrical receptacle connector includes a receptacle insulated housing as well as receptacle terminals and locking components on the receptacle insulated housing. The locking components at the two sides of the electrical receptacle connector are firmly buckled with the buckling portions at the two sides of the electrical plug connector. Therefore, during the use of the electrical connector assembly, the electrical plug connector can be prevented from detaching off the electrical receptacle connector.