In the process of wind power generation, the power curve of wind power generating unit reflects the operating state and the actual generating capacity of the wind turbine. And it is also an important indicator of the performance of the wind turbine. In this paper, a new method — method of grid is proposed based on IEC61400-12-1 standard. In this method, the wind speed — power coordinate system is divided into grid by equally dividing the power axis and the wind speed axis. Then, the data recorded by the supervisory control and data acquisition(SCADA) system could be located through the grid, use the method of segmented filtering to remove the abnormal data. And take the data of a wind turbine as an example to verify the effect of the method. The results show that the method of grid can remove the abnormal data point effectively, and the power curve drawing based on method of grid is more in accordance with the output characteristics of the wind turbine.