The optimizing of land-use structure in Dunhuang was studied with gray multiobjective programming. The results show that. Taking comprehensive benefits of land use as the optimization target, in order to achieve the biggest of society and economic efficiency of land use, the optimization program of land use structure in Dunhuang should decrease the area of cultivated land and grassland about 0.02% and 0.01%, increase the the area of woodland, garden land, constructive land and industry land about 0.05%, 0.01%, 0.11% and 0.06% respectively. Among the limiting conditions of the optimization program of land use structure in Dunhuang, the water limiting is the decisive limiting condition, while promoting the use efficiency of cultivated land and garden land is the root way to achieve the comprehensive benefits of land- use-structure optimization in Dunhuang.