Abstract: Wind farms are usually at the end of the grid, grid port voltage fluctuations will cause varying degrees of phase locked loop（PLL） transient response, so that the grid system cannot render the expected control performance, even leads to instability. Considering the impact of PLL transient characteristics and line parameters on high-power direct drive wind power system converters with LCL filter current control performances, in this paper a current loop PI controller parameter design method based on the multi-objective function was proposed. Firstly, a precise static model of grid-connected current control systems is established. Based on this, by analyzing the amplitude margin, the phase margin and the static errors of the system response characteristics, the PI controller parameter ranges meeting the above requirements had been achieved. Subsequently, a transient grid-connected current control system model affected by phase locked loop performance was established, furthermore the existing PI parameters value interval was optimized to obtain a better performance of the controller parameter combinations. Finally, 1.5 MW LCL type grid-connected converter simulation results and 10 k W experimental platform verification showed that, this method can improve both the static and dynamic responses of the current control and adaptability to the grid environment.