Utilizing composite fuzzy evaluation model, selecting the characteristic evaluation index system of Nanjing City, and taking the year of 2009 as status quo, this paper evaluated the water resource carrying capacity(WRCC) of Nanjing City and obtained WRCC=0.365 4, which indicating that the water resource carrying capacity was at a low level and closed to the critical state of quasi-non-bearing. Then the paper predicted the relevant indexes of Nanjing City in 2020 with the grey prediction method and comprehensively evaluated the water resource carrying capacity of Nanjing City in 2020 reusing the composite fuzzy evaluation model. The result was WRCC=0.490 2, indicating that the water resource carrying capacity of Nanjing City will be still in the category and will be higher than that in 2009. Finally, the paper proposed some strategies to improve water resource carrying capacity of Nanjing City: (1) conserving water and reducing water consumption per capita; (2) controlling natural population growth rate; (3) regulating water structure and reducing water consumption of million GDP; (4) strengthening sewage disposal and reclaimed water utilization levels.