A cooling fan includes a fan frame, a circuit board, a stator-coil unit and an impeller. The fan frame includes a metal seat and a lateral wall. The metal seat includes an engaging face and an engaging portion arranged on the engaging face. The lateral wall is arranged on a periphery of the metal seat and includes an air inlet and an air outlet. The circuit board includes a positioning hole. The circuit board is press fit around the engaging portion of the metal seat via the positioning hole and adhered to the engaging face of the metal seat. The circuit board includes an insulation layer facing the metal seat. The stator-coil unit is mounted on the metal seat of the fan frame and electrically connected to the circuit board. The impeller is rotatably coupled with the stator-coil unit.