A method of making a receptacle connector includes: Step 1: providing an upper terminal module making via a first inserting molded process; Step 2: providing an lower terminal module making via another first inserting molded process; Step 3: stacking the upper and lower terminal modules together in a vertical direction so as to provide a main basis; Step 4: applied an insulative filler on the main basis via a second insert molding process, wherein the insulative filler fills and completes the front tongues of the upper and lower terminal module thereby forming a mating tongue for inserting a plug connector.