A centrifugal fan with a resonant silencer has a centrifugal impeller and an outer housing. The outer housing has an inlet, an outlet and a resonant silencer. An inlet is positioned along an axial direction of the centrifugal impeller. An outlet is positioned along a radial direction of the centrifugal impeller. The resonant silencer, extended from a cut-off, can reduce noise caused by a vortex. The resonant silencer can be I- or L-shaped. The cut-off can be covered by a net filter, which isolates the resonant silencer from the flow motivated by the centrifugal impeller.