Ecological restoration is of great significance in curbing the degradation of urban lake ecosystems. Finding an effective and simple prediction method for ecological restoration effects is conducive to further promote lake restoration research. In this paper, water quality response to ecological restoration is analyzed using comprehensive pollution index method, lake pollutant concentration determination method based on Delphi method and contribution to water quality improvement, and the water quality model based on pollution load balance is used to predict Qianlong lake's water quality under the ecological restoration measures. Results of calculation and evaluation illustrated that all of the concentrations of four pollutants declined and the water quality of Qianlong Lake significantly improved, while the response degree of different pollutants to ecological restoration measures was different. The control of COD concentration requires supports of pollution source control and repair purification. The sensitivity of TN to different measures are close. TP and NH3—N showed highest sensitivity to pollution control and ecological hydrating, respectively. Scenario prediction showed that the ecological restoration scheme based on water quality response relationship enables Qianlong lake to maintain the ecological restoration effect stably.