A receptacle connector for mating with the plug connector, includes a terminal unit, a metallic shield and a mating cavity surrounded by the metallic shield. The terminal unit includes a terminal module having a first insulator with a plurality of first contacts embedded therein via a first stage insert-molding process, a second insulator with a plurality of second contacts embedded therein via the similar first stage insert-molding process. The first insulator includes a first front insulator and a first rear insulator spaced from each other while linked together by the corresponding first contacts; the second insulator includes a second front insulator and a second rear insulator spaced from each other while linked together by the corresponding second contacts.