The invention provides a fan. The fan comprises an impeller, a motor and a plurality of blades, wherein the motor is coaxially connected with the impeller; and one end of each blade is connected with the outer wall of the impeller. The ratio of the distance between the other end of each blade and the axis of the impeller to the radius of the impeller is 0.28-0.32. By means of the technical scheme, the ratio of the distance between the edges of the blades and the axis to the radius of the impeller is optimized and limited, so that the size of the blades is in a limited space, the matching performance of the blade size and the impeller size is improved, and the gas through-flow capacity is effectively improved, that is, the ventilating capability of the fan is improved; and thus, the air volume is increased in the limited space, the space is saved, and the heat dissipation and cooling capability of the fan is improved.