In the isolated small scale wind power generation systems， the load characteristics have special requirements on the inverter. In this paper， the three-phase four-leg topological structure is used. The control model of the inverter based on the symmetrical components is presented， and the expression is deduced in the bisynchronous d-q coordinates. A multi-loop control system based on the feed-forward decoupling control strategy is established， and the independent control among the positive-sequence， negative-sequence and zero-sequence components is realized. Experimental results demonstrate that this control strategy can mitigate disturbances quickly under unbalanced loads and obtain high quality output waveform.