Based on the set law of WRMM model parameters ,and under the condition of given supply water priority order to achieve water resources allocation in the dry years, the paper took Manasi River Basin for example, carried out different operating policy of water resources allocation on varying degrees of dry years(once in twenty years, once in hundred years, extreme dry years). The result showed that WRMM model is reasonable and effective to develop water resources allocation in the dry year. Moreover, the parameter set law in the model made the model easy to operate. And the study made WRMM model facilitate further promotion, and offered great reference value for the water resource management and allocation in dry year in other areas of Xinjiang.