An electrical connector structure includes an insulating body, ground terminals, and a grounding piece. The insulating body has a divider block. The ground terminals are fixed on the insulating body and arranged in two opposite sides of the divider block. Each ground terminal has a docking portion, a main portion, and a tail portion. The main portions are fixed on the insulating body. The docking portions and the tail portions extend from two sides of the insulation body. The grounding piece is fixed on the divider block. The grounding piece has a first mounting plane and a second mounting plane corresponding to the first mounting plane. The first mounting plane and the second mounting plane are located at two opposite surfaces of the divider block, and have contact portions protruding therefrom. The contact portions electrically contact the ground terminals respectively.