Abstract: At present, LID related researches have become gradually integrated and multidisciplinary. In particular, there are increasing discussions on the construction and optimization layouts of LID measures. Taking Gulou District of Nanjing City as an example, this paper establishes a method framework for urban stormwater management evaluation and optimization based on ArcGIS and SUSTAIN. It builds a city-scale hydrological model. Taking the total annual runoff control rate, investment effectiveness and other construction objectives into consideration, it simulates and gets the cost-benefit curves for various LID connection schemes. The research shows that the cost-effectiveness of LID has a certain cumulative effect, and the cost-benefit of LID in the series mode is better than that of the parallel mode. When the scale and cost of LID exceed a certain threshold, the efficiency of runoff control will gradually stabilize. It concludes that the optimal investment cost of Gulou District is 740 million yuan, at which time the overall annual runoff reduction rate can reach 75%. Based on this, it puts forward some suggestions and countermeasures for the construction of LID in Gulou District.