The disclosure provides a centrifugal fan, including an enclosure, a spacer, and a fan blade rotor. The enclosure includes a top panel, a bottom panel, and a side wall connected between the bottom panel and the top panel. The top panel, the bottom panel, and the side wall together form a first air exhaust vent and a second air exhaust vent. The spacer is disposed in the enclosure, is connected between the bottom panel and the top panel, and spaces a first space in communication with the first air exhaust vent and a second space in communication with the second air exhaust vent in the enclosure. The spacer includes a first opening. The first opening is in communication with the first space and the second space. The fan blade rotor is rotatably disposed in the second space.