Wind speed data was reconstructed in phasespace based on chaos theory.The embedding dimension and delay time were first calculated via the CC method.The correlative dimension of attractor was then calculated with the GP method.Finally,the largest Lyapunov exponent of wind speed time series was calculated on the basis of the improved small data sets method.The wind speed is found to be of chaotic property,therefore,the chaosbased prediction method is recommanded to further improve the prediction accuracy of wind speed time series in wind farm.