A brushless motor assembly includes a motor body, a circuit board, and a plurality of electronic elements. The circuit board is disposed on the motor body and has a first surface and a second surface which face opposite directions. The first surface faces the motor body. The second surface has a plurality of thermoconductive layouts. The electronic elements include a plurality of power switching elements disposed on the second surface. A plurality of heat sinks is disposed on the second surface. Each of the power switching elements and each of the heat sinks are connected to each of the thermoconductive layouts, so that a thermal energy generated by each of the power switching elements is transferred to each of the heat sinks through each of the thermoconductive layouts. This configuration thereby reduces an overall volume of the brushless motor assembly.