An electrical connector includes: an insulating block, provided with at least one adjusting groove; and a plurality of terminals, fixed to the insulating block and arranged in at least one row. The terminals include at least one pair of differential signal terminals and at least two ground terminals. Each of two opposite sides of the pair of differential signal terminals is provided with a corresponding one of the ground terminals. The adjusting groove is provided between only one of the two opposite sides of the pair of differential signal terminals and the corresponding one of the ground terminals, such that electric charges and electric fields between the pair of differential signal terminals and the ground terminals at the two sides are not distributed uniformly, thus reducing the ground mode resonance of the ground terminals to the differential signal terminals, and improving the high frequency performance of the electrical connector.