Abstract: In order to study the effects of salinity and pH on the growth and lipid content of freshwater diatoms, we studied a strain of Navicula trivialis from field water samples, by setting different salinity 0, 0.03, 0.06, 0.12, 0.18, 0.24 mol/L and pH 4.5, 6.0, 7.5, 8.5, 9.5 and 10.5 concentration stress. The effects of each treatment on the growth, chlorophyⅡ a content, chlorophyⅡ fluorescence parameters and lipid content of Navicula trivialis were determined. The results showed that the cell density and chlorophyⅡ a content of Navicula trivialis were the highest when the NaCl concentration was 0.12 mol/L and pH 7.5; When NaCl concentration was 0.24 mol/L and pH 7.5, the total lipid content was the highest, which was 34.93% and 33.5%, respectively. The results showed that the adaptability of Navicula trivialis to different salinity and pH was different, which affected its growth and lipid content to some extent. Finding the best culture conditions to improve the growth and total lipid content of Navicula trivialis provides basic data for the study of microalgae culture, and the regulation of salinity and pH can provide scientific basis for the large-scale culture of Navicula trivialis. At the same time, the sensitivity, response and adaptability of Navicula trivialis to the salinity and pH, which will affect the phytoplankton community under environmental changes to a certain extent. the study provides a new idea for in-depth discussion of the impact of salinity and pH changes on phytoplankton community structure.