An electrical connector assembly (100), comprises: an insulative housing (2) having a plurality of passageways (24) arranged into a first row and a second row; a plurality of terminals (3) received into the corresponding passageways of the insulative housing and divided into a first terminal group (31) and a second terminal group (32), and each terminal having a terminating section (303) at a rear end thereof, the terminating sections of the plurality of terminals located on a common plane; a spacer (4) assembled to a rear end of the insulative housing and having a row of grooves (421) formed on an upper surface thereof, the terminating sections of the terminals passing through the spacer and received into the corresponding grooves of the spacer; and a metallic shell (5) assembled to an outer surface of the insulative housing and the spacer.