To solve series of problems in exploitation of water resources, such as shortage of water resources, unreasonable structure of water use, severe pollution of water quality, low efficiency of water use and waste of water resources, and to realize the sustainable utilization and reasonable allocation of water resources in Maliba Irrigation District of Longchuan County in China, a model for allocation of water resources is established by using the MIKE BASIN software. The results of allocation of water resources under reliability of 80% are given. The results show that by means of the combined dispatching of Maliba Reservoir, nearby small reservoirs and newly-built reservoirs, the water demand in this area can be basically satisfied.