Abstract: A multi-bjective model for calculating the optimal water resources  allocation and carrying capacity is established on the basis of the water availability and water resources utilization limit in the foreseeable period in Wenshan autonomous prefecture. The model aims to maximize the economic and social benefit and food security and to restrain the water use. SPSS software is adopted for curve fitting and significance test, and the genetic algorithm toolbox of MATLAB2010a software is used for optimization calculation. The results show that, first of all, constrained by water availability in the foreseeable period, Funing County and Malipo County have the largest water resources carrying capacity with the critical value to be in 2075 and 2040； while Yanshan County and Wenshan County have the smallest carrying capacity with the critical value in 2015 and 2025. Secondly, constrained by water resources utilization limit, Malipo County, Funing County and Xichou County have the largest carrying capacity with the critical value respectively in 2160, 2063 and 2061； whereas Yanshan County and Wenshan County have the smallest carrying capacity with the critical value in 2024 and 2040. Finally, judged from the current water technology and life standard, the optimal allocation and the carrying capacity calculated by the model are consistent with the trend and scale of regional economic and social development.

Key words: optimal allocation, carrying capacity calculation, water resources, genetic algorithm