Abstract: The effects of different concentrations of copper and magnesium ions on the photosynthetic pigments and hemolytic activity of Chattonella ovate were studied, and the relationship between hemolytic activity and photosynthetic pigments was further discussed. The results showed that the growth condition of C.ovata was optimum when the concentration of copper and magnesium was 7.84 μg/dm³ and 18.79 g/dm³, respectively. Under the treatment of different concentrations of copper ions (3.92, 5.88, 7.84 and 9.80 μg/dm³), the high concentration of copper ions (9.80 μg/dm³) inhibited the accumulation of fucoxanthin and diadinoxanthin of C. ovata. With the increasing magnesium ion concentration (7.52, 11.27, 15.03 and 18.79 g/dm³), the average content of chlorophyll c2 and diadinoxanthin increased, while the average content of violaxanthin and fucoxanthin did not change significantly. The hemolytic activity of C. ovata increased with increasing metal ion concentration, which was consistent with the changes of chlorophyll c2. Factor analysis of hemolytic activity and photosynthetic pigment indicated that the hemolytic toxin was closely related to chlorophyll c2, which is possibly chlorophyll c2 or its analogue.