In this paper, random fluctuation on river water quality parameters is analyzed and studied, and it is specially that the Ito random differential equation of water quality is represented. The solution to Ito equation is a Markov process. By means of the Fokker-Plank equation, a set of differential equations which satisfy the moments of the solution process of the Ito equation is determined, thus, to derive a set of corresponding moment equation and correlation or cross-correlation functions of x,1,&, x ,2, According to Wiener filter theory, the optimal pulse respone characteristic is developed to monitot and predict the river system’s quality, thereby bring about controlling and administering on river pollution.