A voltage control strategy of the converter inverter-stage is proposed for the variable speed direct drive wind power system which consists with the two stage matrix converter (TSMC) and the permanent magnet synchronous generator (PMSG). In this control strategy, the inverter-stage voltage is controlled by the adjusted of inverter-stage modulation ratio M. For two cases, which is strong wind speed and weak wind speed, the ways that is decrease M and increase M are used and obtain the wide wind speed capture range. The resulted of simulation and experiment show that this way can make the voltage stabled. The performance of the converter implement this control strategy is still as same as the dual PWM converter and the wind power system preserve the feature of the wide wind speed capture range. So this way is effective and feasible to some extent.