Abstract: Jiucaiping wind farm of Guizhou province locates in a large mountainous area, and the wind speed of each wind turbine in wind farm is always correlative. In this paper, multivariate normal Copula function and rank correlation matrix are used to quantify the coherence of wind speed in the wind farm so as to build the wind speed model which can reflect the wind speed characteristics of the wind farm. The Weibull wind speed distribution, cumulative distribution function of wind speed and multivariate normal distribution sequences can be joined by multivariate normal Copula function effectively, which realizes the transform and modeling prediction of relative wind speed. Furthermore it can provide certain technical support for analyzing the influence of wind speed of Jiucaiping wind farm on the stability of power grid security in this region. It also can provide some references to the planning and development of wind farms in the mountainous area and large wind farms as well.