By building a comprehensive evaluation index system of urbanization and water environment, using entropy method, mean square error method and AHP, We calculated the weight of each indicator in urbanization system and water environment system in Yellow River Delta between 1995 and 2012, and find the key indicator in the system. By comparing the trends of urbanization and water environment system, we conclude that the impact of the urbanization on the water environment state is significant at the initial stage and weaker in the later stage. On the contrary, water environment have a little effect on the development of urbanization over the whole process. The coupling coordination degree model of the urbanization and water environment of Yellow River Delta shows that during 1995-2012, the urbanization system and water environment system were experienced moderate disordered development with the lowest coupling degree from 1995 to 1998, disordered development with conflicts from 1998 to 2002, barely balanced development with coordination from 2002 to 2007, and well balanced development with harmony from 2007 to 2012, respectively. Since 2007, the development level of the urbanization in Yellow River Delta keeps high. Water environment pollution prevention and control measures play important role in region, so making the water environment maintaining a good state.