The utility model discloses an electric connector (1), which comprises a fastening piece (4) and an insulation body (3) provided with a front surface (302) and a back surface (303), wherein, the insulation body is provided with a plurality of containing slots (305) and passages (308), a plurality of conductive terminals (6, 7) are reliably contained in the containing slots and the passages, and the insulation body is also provided with three rows of first, second, and third projections (34, 36, 38) which are parallel which the front and the back surfaces; the fastening piece comprises an inner surface (44) and a plurality of slot passages (400, 402) dented on the inner surface, and each slot passage is provided with convex parts (404, 407); the convex parts can be held between the second and the third projections before the electric connector is installed on a circuit board and can be reliably matched with the first projections after the electric connector is installed on the circuit board. By the structure, the electric connector can be reliably connected with the circuit board, and the electric connector is prevented from generating rotation corresponding to the circuit board.