Abstract: In order to improve the estimation accuracy of wind resource assessment and reduce the cost of wind measurement for distributed wind power projects with low wind speed,based on the study of the estimation and extrapolation of the three-parameter Weibull distribution parameters,a three-parameter Weibull distribution parameter vertical extrapolation method based on Probability Weighted Moments Method（PWMM） is proposed.Using the probability weighted moments of wind speed statistics at the lower height,the wind speed parameters of the Weibull distribution in the flat terrain at a higher height are obtained by vertical extrapolation,then the Weibull distribution function and wind power density are obtained.The analysis of the example shows that the three-parameter Weibull distribution parameter vertical extrapolation method based on PWMM has certain applicability at different wind speed measurement points of flat terrain.It also can effectively reflect the wind speed distribution characteristics of the flat terrain with low wind speed,and improve the accuracy of wind power density evaluation.