An electrical connector assembly includes a first electrical connector and a second electrical connector mated with each other. The first electrical connector includes an insulative housing, a plurality of conductive terminals and a grounding plate. The insulative housing extending along a longitudinal direction includes a base portion and a plurality of side walls extending forwardly from the base portion and forming a mating cavity. The insulative housing defines a plurality of first passageways and second passageways separately formed in two opposite side walls thereof communicating with the mating cavity. The conductive terminals include a plurality of first terminals and second terminals received in the corresponding first and second passageways. Each of the first and second terminals has a contact portion extending into the mating cavity. The grounding plate is disposed between the first and second terminals and defines at least one pressing portion located in the mating cavity.