An electrical connector includes an insulating block, and multiple differential signal terminals and multiple ground terminals embedded in the insulating block. Multiple first protruding blocks and multiple second protruding blocks protrude and extend forward from a front surface of the insulating block. A slot is formed between the first protruding block and the second protruding block adjacent to each other. Each differential signal terminal is embedded in and extends forward out of a first protruding block. Each of left and right sides of one pair of differential signal terminals has a first side surface. Each ground terminal is provided between two adjacent pairs of the differential signal terminals, and is embedded in and extends forward out of a second protruding block. Each of left and right sides of the ground terminal has a second side surface. A medium between the first side surface and the second side surface is air.