Fan motor silent at high speed

A fan motor silent at a high speed, comprising a casing, a rotor, a stator assembly and a hollow bearing support, wherein the stator assembly and the bearing support are sequentially and coaxially nested and fixed in the casing, a first bearing and a second bearing are coaxially mounted at two ends of the bearing support, inner iron cores are inlaid in the bearing support at intervals, two ends of the rotor are rotatably inserted into inner holes of the first bearing and the second bearing respectively, a through air duct is arranged between an outer wall of the stator assembly and an inner wall of the casing, an impeller opposite to the air duct in position is fixedly mounted at an exposed end of the rotor and located in the casing, and air guide vanes which are distributed in an axial direction of the rotor and incline in a same direction are arranged on an inner wall of the air duct at intervals.