Permanent-magnet synchronous generator (PMSG) based directly driven wind turbine is connected to grid through the grid-side converter (GSC), grid voltage swell fault directly affects the operation of grid-side converter. In this paper, the analysis of the voltage and current constraints of the GSC under grid voltage swell is given firstly, and then a high voltage ride-through (HVRT) control strategy is proposed, which is based on the modulation voltage closed-loop control. The proposed control strategy can ensure the normal operation of the GSC within the limited voltage swell. Finally, simulation results demonstrate the effectiveness of the proposed control strategy.