An electrical connector mounted to a circuit board, includes an insulating housing, a plurality of terminals integrally molded to the insulating housing, a shell surrounding the insulating housing, and an upper cover covered on the circuit board. The shell has at least one lower fastening piece. At least one tongue board of the circuit board is fastened on the at least one lower fastening piece. Circuit lines equipped on a bottom surface of the at least one tongue board are embedded in lower embedding slots of the at least one lower fastening piece. The upper cover has at least one upper fastening piece. The at least one upper fastening piece is fastened on the at least one tongue board. Circuit lines equipped on a top surface of the at least one tongue board are embedded in upper embedding slots of the at least one upper fastening piece.