21 main streams and tributaries of typical rivers in Jiangsu Province were taken as the research objects to evaluate river ecological status under the background of urbanization in this paper. A system of river ecological evaluation indexes and the evaluation model for plain river network area were constructed, including 4 indexes of aquatic environment, natural ecological system, social service function and water management and protection, and 12 pieces of divided criteria. The ecological status of these rivers in Jiangsu Province was evaluated, of which 71.4% were good. Analyzing the impact of urbanization on the ecological condition of rivers, we came to the conclusion that the level of river ecological status is decreasing with the improvement of urbanization level, and put forward that the reference value of the ISC red line of river ecological condition from good to medium in the urbanization plan of ecological river construction is 28%.