According to one aspect of the present invention, an electrical connector assembly includes a locking station and a plug cable connector. Said locking station has a receiving cavity, and a pair of side walls extending in a front-to-back direction and locating at two sides of the receiving cavity in a transverse direction perpendicular to said front-to-back direction. Said plug cable connector is forwardly inserted into said receiving cavity and includes a spring being deflectable in a vertical direction perpendicular to both said front-to-back direction and said transverse direction. Said spring includes a pair of laterally extending offset ends; and each side wall defines a locking shoulder facing forwardly and pressing against said respective offset end downwardly.