Based on the data including industrial, agricultural and daily domestic water consume from the communiques of water resources in Xiamen(1999-2010), information entropy was used to describe the process of water utilization structure. By use of grey relational degree analysis , the major driving forces of the change were found out. The results indicate that the information entropy and balance degree of water utilization structure in Xiamen is approaching to the maximum since 2006. The more the number is close to the maximum, the more the balance system becomes. Water utilization structure tends to disorder and equilibrium. Grey relational degree reflects that the socio-economic development has a strong impact on the evolution of water utilization structure, especially the industrial structure.