AC and DC brushless motor for the fan, comprising a brushless motor; and an active power adjustment mechanism, disposed within the brushless motor and comprising an EMI filtering and rectifying unit, a prior driving unit connected to the EMI filtering and rectifying unit, a motor driving unit connected to the brushless motor, a constant current unit connected to the EMI filtering and rectifying unit and the prior driving unit, a protective compensation unit connected to the prior driving unit and the constant current unit, a motor controlling unit connected to the motor driving unit, and a sensing unit connected to the motor controlling unit.