Abstract: The establishment of scientific forewarning system is an important means to solve the crisis of water environment in China. In order to make the correct, fast and intuitive forewarning, this paper introduced Weber-Fechner’s Law from the field of psychology, took water quality monitoring sections of Sanhetun and Ajipu as cases in Liaohe basin, and selected the important water environment quality evaluation indices for the study. On this Basis, the weights of various indicators were determined using entropy Law method, and the values of water environment warning of the two sections were calculated, and the warning models between water level and water environmental quality index were established, in order to quantify the quality of water environment. The results showed that: the level of Sanhetun section was overweight, Ajipu had on no warning status. Therefore, this model can be used for water warning and water quality evaluation in the Liaohe River Basin.