We have monitored and analyzed water environment for Niyang River, the branch of the Yarlung Zangbo River, Tibet, based on seasons from November 2008 to October 2009. The results are as follows: Firstly, based on Pearson correlation matrix, physico-chemical factors for Niyang River can be divided into three categories, which are low correlation physicochemical factors, mid correlation physico-chemical factors and high correlation physico-chemical factors. Secondly, based on factorial analysis, physicochemical factors for Niyang River can be divided into four categories, which are normal physico-chemical factors, hardness relevant physico-chemical factors, elevation, and physicochemical factors affecting growth of aquatic organism. Thirdly, based on PCA, the characteristics of level period, wet season and dry season are significantly different, there is no difference along Niyang River from upstream to downstream. Last but not least, we have structured regression equation between elevation and relevant physicochemical factors, regression equation between bottom water temperature and relevant physicochemical factors. The paper also suggests paying close attention to water environment monitoring, in order to warrantee the sustainable development of Niyang River aquatorium ecology.