According to the quality of municipal reclaimed water, the cascade water principle is implemented in Guodian Changcun No.1 Cogeneration Power Plant to improve the water reuse rate, and the waste water reduction technology that waste water during desulfurization process being sprayed into boiler flue to evaporate, has been applied to achieve zero water emission in the whole plant. The design of zero water emission in power plant adopts the technologies as follows: the circulated water used bypass lime treatment system, whose effluent is preferred for boiler makeup water, the rest is back to the circulated water system; the boiler makeup water treatment system uses integrated membrane treatment technology which adapted to the concentrated reclaimed water and could significantly reduced the amount of waste water; Ⅰ reverse osmosis concentrate and pulp of lime treatment system are sent to the flue gas desulfurization system for repeated use. In the zero water emission mode, there were many types of makeup water in the flue gas desulfurization system and the water quality is complicated. So the choose of repeated application should be determined according to the water quality condition. Meanwhile, in the zero water emission system higher requirements are imposed towater management of power plant.