In the course of a urban man-made lake development,on the one hand,due to the high expectation on water landscape,the demand on water quality criteria of the lake is high;on the other hand,due to the frequently human activity on the lake and the low capacity of contamination of the lake,it is difficult to maintain high water quality criteria.Taking one planning urban man-made lake as an example,this paper put forward that three main factors must be integrated considered while setting the water quality criteria for the lake:water quality of the supplied source water,pollutant load of the lake,self decontamination faculty of the lake.Based on collected data,possible pollutant load to the lake from rainfall,rainfall runoff and bottom of the lake are estimated.TP model was built to predict final water quality of the lake.