Abstract:In order to explore the optimal conditions for the accumulation of astaxanthin by Haematococcus pluvialis，the effects of light intensity，NaNO3and NaCl concentration on photosynthesis and the accumulation of astaxanthin were studied and the results showed that Fv/Fm in the treatment group with different light intensity was significantly lower than that in the control group （P＜0.05）；on the 24th day of the experiment，the maximum value of the astaxanthin accumulated by microalgae in the experimental group with the light intensity of 236 μmol/m2/s was 9.01 mg/L.Fv/Fm and Yield value of H.pluvialis at NaCl concentrations of 10，12.5 g/L were lower than those of the control group，while Fv/Fm and Yield values of H.pluvialis at NaCl concentrations of 5 g/L were higher than those of the control group.When NaCl concentration was 5，7.5，10 g/L，the content of astaxanthin accumulated in microalgae was significantly higher than that in other experimental groups（P＜0.05）；on the 24th day of the experiment，when NaCl concentration was 7.5 g/L，the content of astaxanthin ac－cumulated in microalgae reached the highest level，34.4%higher than that in the control group.When the concentration of NaNO3was 0，0.032，0.065 g/L，the Fv/Fm of H.pluvialis presented an overall trend of rising first and then slowly decreasing，which was significantly different from that of the control group（P＜0.05）.Under nitrogen stress condition，the content of astaxanthin accumulated by H.pluvialis increased gradually，and the astaxanthin level within cells became stable after 22 days.When NaNO3concentration was 0，the astaxanthin content within cells was significantly higher than that of other experimental group（P＜0.05）.