The invention provides a stepped
volute structure, a
centrifugal fan and an air blowing device. In the stepped
volute structure, a plurality of
volute tongues and volute volute-tongue side wall surfaces are arranged in a stepped mode and extend in the thickness direction from an air inlet to a shell. The distances from the volute volute-tongue side wall surfaces to a front blade disc are graduallyincreased, so that on the height volute section nearby the front blade disc, the overall width of a volute
diffusion section is reduced, namely the volute tongues and the volute volute-tongue side wall surfaces are closer to a volute
throat side wall surface. Since high-speed
airflow impact is close to the volute-tongue side wall surfaces, the situation that a negative pressure area is generatedlike a traditional centrifugal volute is avoided, generation of whirling
airflow is restrained, and thus an
eddy current whirling area of a
diffusion section of the traditional centrifugal volute is eliminated. After the whirling
airflow area on the height volute section nearby the front blade disc is
cut off, the disturbance of the whirling airflow on normal acting and air exhausting of the volute is eliminated, and thus the
air volume is increased; and meanwhile
eddy current noise disappears accordingly, and thus
noise is reduced.