The AC-DC-AC structure of non-controllable rectifier and controllable inverter is used for grid-connected circuit of the direct-drive permanent-magnet synchronous wind generator. According to the relationship of rotational speed， power and DC bus voltage， observing rotational speed by using DC bus voltage is proposed to realize none direct speed measurement. The wind turbine characteristic and grid-connected power model are analyzed， and the direct-control grid-connected power to realize tracking maximal wind energy is proposed without controlling generator. The decoupling control of active and reactive power is realized and the numerical range of active and reactive power is given. The current hysteresis-band control is used to control inverter. Simulation results demonstrate the good static and dynamic performance of the proposed control strategy.