A recirculation fan includes a casing, a covering member, and a fan assembly. The casing has a base. The covering member is coupled with the casing to define an accommodation space. The fan assembly is disposed within the accommodation space, and includes a first impeller, a second impeller, a motor, and a plurality of magnetic elements. The second impeller is located beside the first impeller. The motor is fixed on the base of the casing and connected with the first impeller for driving rotation of the first impeller. The magnetic elements are arranged between the first impeller and the second impeller. A wind force generated by the first impeller and a magnetic torque resulted from a magnetic vortex of the magnetic elements cause contactless rotation of the second impeller.