The correlation of wind speed and illumination should be considered in the Wind/Solar Hybrid Generation System. The establishment of the joint distribution function has important sign ificance to reducing the deviation of distribution network reliability evaluation.This paper uses th e maximum wind speed and illumination in a year in Hohhot area as sample, and uses kernel dens ity estimation to get the cumulative distribution function of wind speed and illumination ,then st ructures the binary joint distribution function through three Archimedes Copula function. After ge tting the edge distribution of the wind speed and illumination distribution , this method can easily gets specific binary joint distribution function expression only throughing test the parameter of fu nction whether meets to the requirements.Besides ,this method avoids complicated calculation pr ocess in the conventional mathematical modeling method, and it also chooses the optimal copula function based on the minimum fitting error.