The invention discloses an extended active power-based sliding mode variable structure direct power control (DPC) method for a DFIG in an unbalanced power grid. Extended active power is provided on the basis of a mathematical model of the DFIG in the unbalanced power grid, the extended active power and conventional reactive power are taken as control objects, a sliding mode variable structure algorithm and a DPC technology are combined, and an improved extended active power-based sliding mode variable structure DPC strategy is further provided. According to the method, the DFIG in the unbalanced power grid can be effectively controlled to obtain stable electromagnetic torque and reactive power as well as sinusoidal stator current on the premise of no positive and negative sequence separation of the voltage and current of the power grid; control can be systematically implemented simply without monitoring the frequency of the voltage of the power grid in real time by a phase-locked loop.