Abstract: The stepwise multiple regression statistical method was used to calculate the relation between diatoms assemblages and 8 environmental factors such as DO, ammonia nitrogen (AN), pH, water temperature (WT), BOD, COD, TP, TN base on the abundance and richness of diatoms in Songhua River, Harbin. The value function graphs were established for each individual parameter and whether the environmental quality is improved or not was observed. The results showed that some taxa of diatoms were related to pH, WT, TN, BOD, AN, the most significant factor is pH. Moreover, the diatom assemblages perfectly predicated the changes of the river.

Key words: diatoms, multiple regression, prediction, Songhua River in Harbin