Abstract: The response of Nitzschia palea to increase in NaGl concentration (0—1.0 mol/L) in the growth media was studied. The alga showed a wide adaptability to salinity. It was able to grow in media containing≤1.0mol/L NaCl, and optimal growth was observed at 0.25mol/L NaCl (S‰=18‰). The contents of main biochemical constituents of cells grown at different NaCl concentrations varied various degrees. A slight increase in the ratio of carotinoid to chlorophyll was observed with increasing salinity due to a decrease in chlorophyll content in the cells. There was no significantly variation in protein content of the cells grown in the media with different levels of NaCl. However, the relationship between the carbohydrate content and the NaCl concentration was found to be linear. Morever, the total amino acid contents of N. palea increased markedly with increases in NaGl concentration from O to 0.75 mol/L in growth media. The results suggested that carbohydrates and free amino acids in the ceils of N. palea were major osmotic regulators during adaptation to externaal salinity changes.