Heat dissipation device of brushless motor

A heat dissipation device of a brushless motor disclosed by the present invention comprises a head shell, a heat driving device, a promoting device, an adjusting device, a middle shell and a barrel, the heat driving device structurally comprises a first magnetic block, a power coil, a rotating shaft sleeve, fan blades and a water cooling device, and the rotating shaft sleeve is rotatably connected to the axial interior of the head shell. A first magnetic block is fixedly connected to the axial inner side of the rotating shaft sleeve, a power coil is fixedly installed on the axial inner side of the first magnetic block, and fan blades are fixedly connected to the axial outer side of the rotating shaft sleeve. According to the heat dissipation device of the brushless motor, through the cooperation among an annular groove, a hole groove and the fan blades, the purpose that heat generated by mutual contact friction between the rotating shaft sleeve and the inner side wall of the middle shell when the rotating sha