Abstract: According to the investigated water demand of various sub-regions in the lower reaches of Tarim river,the paper establishes and solves the optimal alocation model for the water deliveries by using the nonlinear optimization theory with the constrained conditions. By employing the famous Kuhn-Tucker condition method,this paper solves the optimal allocation model for the water deliveries to the lower reaches of Tarim River and obtains the reasonable allocation of water quantity for various sub-regions of the lower reaches of Tarim River. The result indicates that the improved eco-area of 1490 km² is achived through the water deliveries(3.4×10⁸m³)to the lower of Tarim river.This reasonable al ocation model of water quantity will provide technical support for the water deliveries in times of emergency in the future.