A centrifugal fan and a dryer, where the centrifugal fan includes a shell, a driving mechanism, an impeller and a volute tongue arranged in the shell, the driving mechanism is connected with the tongue and can drive the tongue to rotate between a first limit position and a second limit position, the tongue includes a first volute tongue part and a second volute tongue part; when the tongue is located at the first limit position and the impeller rotates forwards, the first tongue part abuts against the inner wall of one side of the shell in a sealed mode, the second tongue part can cut the air blown by the impeller, and when the tongue is located at the second limit position and the impeller rotates reversely, the first tongue part can cut air blown by the impeller.