Diatoms are used for monitoring and evaluating the quality of river water. Some European countries have evaluated the quality of rivers and lakes water by diatoms. But now in China, the biological monitoring system of diatom has not been built. In order to built the system, we should study on the relationship between diatoms and physcicochemical factors. The quantitative investigation of the benthic diatoms in the middle and upper of Wujiang River has not been reported yet, as well as the relationshi...