Using the information entropy theory to characterize the change trend of water consumption structure, using the principal component analysis method to determine the principal components of each influencing factor, and using the grey incidence theory to analyze the correlation coefficient between the principal components and the water consumption structure, a study on the change and driving forces of the water consumption structure in Nanjing City was carried out. The results show that the information entropy increased from 1. 532 nat to 1. 791 nat and the balance degree increased from 0. 787 to 0. 861 from 2000 to 2014, indicating that the water consumption structure is becoming more stable. Factors such as economic structure, water-saving technology, population evolution, and water demand are main driving forces influencing the water consumption structure in Nanjing. Measures for total quantity control of water consumed are put forward to guarantee the reasonable utilization of water resources.