The invention discloses a 
noise-reducing method for an electric fan based on blade modification and an improved blade structure of the electric fan. The method comprises the following steps of: (1) establishing a hydromechanic calculating model of an original blade structure of the electric fan; (2) performing 
kinetic analysis on the original blade structure of the electric fan to obtain 
fluid field data and monitoring the 
sound pressure level of 
noise of a preset measuring point, wherein the 
fluid field data comprises a blade surrounding vorticity value and vortex structure distribution; (3) performing a modified design on the 
fan blade structure of the electric fan continuously and performing 
kinetic analysis on the modified blade structure of the electric fan to obtain 
fluid field data and measured point 
noise data, and reducing the blade surrounding vorticity value and crushing large vortexes into small vortexes till the 
sound pressure level of noise of the preset measuring point is reduced on the premise that the blast capacity is invariable at same input power; and (4) manufacturing a fan model, measuring the blast capacity and the 
sound pressure level through experiments, and verifying the reducing effect of the sound 
pressure level of the noise of the measured point. By modified 
noise reduction on the blade of the fan by means of computational fluid 
mechanics, the method is high in pertinence and high in 
operability.