Abstract: To investigate the effect of Ca²⁺ on biomass,the content of chlorophyll,carotenoid and phycobiliproteins of Arthrospira, Arthrospira strain TJSD091 was taken as the research object in this experiment,different concentrations of Ca²⁺ was added in AB liquid culture medium respectively,and the biomass,the content of chlorophyll,carotenoid and phycobiliproteins at the end of the rapid growth period of Arthrospira were determined.The results showed that when the concentration of Ca²⁺ was 0.02 g/L,the PC and APC were the highest,which were 7.607 mg/L and 5.608 mg/L respectively.When the concentration of Ca²⁺ was 0.06 g/L,the biomass,content of chlorophyll and carotenoid were relatively low,which were A₍560 nm)= 0.789,5.149,0.193 mg/L respectively.When the concentration of Ca²⁺ was 0.08 g/L,the biomass,content of chlorophyll and carotenoid were relatively high,which were A₍560 nm)= 1.193,16.13,0.257 mg/L respectively.The variance analysis showed that the concentration of Ca²⁺ had a significant effect on the biomass and the contents of chlorophyll,carotenoid and phycobiliprotein( p < 0.05).