An electrical connector assembly includes a plug, having a body and multiple pins positioned on the body, and a socket connector including an insulating body. Each pin has an insertion portion extending downward out of the body. The insertion portion has a guide surface, and two contact regions located above the guide surface. The guide surface passes through a vertical center line of the insertion portion. Multiple accommodating holes run through the insulating body vertically. Multiple terminals are respectively accommodated in the accommodating holes. Each terminal is provided with two clamping portions. The guide surfaces guide the pins to be inserted downward into the accommodating holes. When each pin is inserted downward to a final position, the insertion portion is located between the two clamping portions, the two clamping portions are correspondingly in contact with the two contact regions, and the guide surface is located below the two clamping portions.