The centrifugal fan of the present invention comprises a frame, a rotatory means and an impeller. Among these, the frame has a first intake, a second intake, at least one air outlet and a plurality of ribs crossing the second intake. The rotatory means mounted in the frame. The impeller further includes a hub, a partition, a plurality of first blades and a plurality of second blades. The hub is coupled to the motor. The partition separates the inlet air of the first intake and that of the second intake so as to reduce the noise caused by the disturbance. A plurality of first blades and second blades are formed on the first surface and the second of the impeller, respectively. Each of the first blades and second blades selectively include a cut corner formed thereon. The second blade and said rib forms an intersection angle of about 90 degrees as the second blade crosses the rib.