A brushless motor includes a rotor, a plurality of sets of stator windings, a position detection assembly, a MOSFET assembly, an inductance detection module and a main control module that controls them. The position detection assembly has a plurality of detection elements for detecting a position of the rotor and a position detection module for receiving signals fed back from the detection elements with the position detection module being electrically connected to the main control module and feeding back the positional information of the rotor thereto. The main control module alternatively switches between the position detection assembly and the inductance detection module to detect the position of the rotor. When the motor runs at a low speed, the system may effectively judge the position of the rotor to enable the machine to start with a load and, when the motor runs at a high speed, the system may accurately judge the position of the rotor, correctly drive the motor to run, eliminate errors caused by assembly, and prolong the service life of the motor.