An electrical connector includes an insulating housing. The insulating housing includes a base having a top surface, a bottom surface opposite to the top surface and a plurality of sidewalls having a top surface high than the top surface of the base. The top surface of the base and the sidewalls commonly form a first receiving room. The base defines a second receiving room of a notch shape running through the top and bottom surface of the base and a first sidewall of said sidewalls. A row of passageways is located in the base and far away from the first sidewall. The first sidewall adjacent to the second receiving room is defined as two opposite stopping walls.