The invention discloses an impeller capable of increasing centrifugal pump noise tone quality and a design method thereof and belongs to the technical field of pumps. Normally, the blades of the impeller of a pump are distributed in an equal-distance manner and the exit edges of the blades are located on the same axial surface, so that intense dynamic and static interference exists between the blades and partition tongues, large noise energy is generated, the noise energy gathers under the signal blade passing frequency, the noise spectrum change shapely, and noise tone quality is poor. The impeller has the advantages that the distance between every two blades are optimized through a rotor automatic balance theory, a plurality of passing frequencies are generated, the noise energy gathered under the single blade passing frequency is reduced, corresponding noise pressure peak is reduced, the reduced noise energy is dispersed to other passing frequencies, stability of the noise spectrum is improved, the exit edges of the blades are allowed not to be located on the same axial plane, interference between the blades and partition tongues is weakened to a certain degree, the noise energy is reduced, overall noise amplitude is reduced, centrifugal pump noise tone quality is increased to a certain degree, and the impeller has certain popularization value.