This thesis explores the evaluation and forecast of the water quality of Yangtze River. The general evaluation of water quality and the pollution situation of related regions are concluded by analyzing the attachment qualitatively as well as quantitatively. Firstly, by building the water quality model to neglect the dispersion coefficient of one-dimensional steady state, we can calculate the index of CODMn and the main region polluted greatly by NH3-N respectively. Then, by analyzing the pollution at the branch and local region, we can find the origin. In the respect of the forecast for the development in the following ten years, we adopt the method of line-fitting process and least squares to analysis and solve, so we can master the trend. And, in the respect of disposal of the polluted water, we adopt the model of calculating the capacity ignorant of the mixed area, so we can solve the problem by building new model. Finally, according to the result of statistics analysis, we put forward the reasonable proposal and suggest to solve the problem of the problem of the water pollution in Yangtze area.
Keyword： Fluid matter of Yangtze River; sour salt index number of high manganese; the ammonia nitrogen density; environment capacity of water