Direct power control based on sliding mode control (SMC-PDC) can achieve its control purpose and constant switching frequency control simply under coordinate system without the complex d-q transformation. When the grid voltage is unbalanced, this paper sets three control objectives to control system, namely eliminating negative sequence current, eliminating active power fluctuation and eliminating reactive power fluctuation. In order to improve control accuracy, T/4-shift method is adopted to extract only positive sequence current component and negative sequence voltage component and there is no need to extract negative sequence current component. So different control commands can be achieved through corresponding power component compensation of three control objectives set before. The simulation and experimental results verify the strategy’s correctness and effectiveness.