Water ecological carrying capacity of basin is important basis to whether coordinated development for basin resources, environmental and economic society, is important means to impetus sustainable development of water ecological environment and social economy. Take Tieling section of Liao River as an example, through the diagnosis of the ecological environment problem, according to the water resource, environment, and the social economy, 8 indexes are selected to establish evaluating indicator system, then use the fuzzy comprehensive evaluation method to calculates water ecological carrying capacity in Tieling section of Liao River. Result demonstrated: in 2009, the score value of water ecological carrying capacity of Tieling section is greater than that of 1999. The little advance of ecoenvironmental carrying capacity related to water in 2009 comparing with in 1999 was due to the decrease of water demand and waste water discharge in per unit industrial added value, and the advanced level of waste control.