Orthogonal combination design was adopted in examining the Spirulina platensis (S.platensis) yield and the influence of four factors (Se content, Se-adding method, S content and NaHCO 3 content) on algae growth. The results showed that Se content, Se-adding method and NaHCO 3 content were key factors in cultivation conditions of Se-enriched S.platensis with the optimal combination being Se at 300mg/L, Se-adding amount equally divided into three times and NaHCO 3 at 16.8 g/L. Algae yield had a remarkable correlation with OD 560 and floating rate by linear regression analysis. There was a corresponding relationship between effects of the four factors on algae yield and on OD 560 , floating rate too. In conclusion, OD 560 and floating rate could be served as yield-forming factors. Orthogonal combination design was adopted in examining the Spirulina platensis (S.platensis) yield and the influence of four factors (Se content, Se-adding method, S content and NaHCO3 content) on algae growth. The results showed that Se content, Se -adding method and NaHCO 3 content were key factors in cultivation conditions of Se-enriched S. platensis with the optimal combination being Se at 300 mg / L, Se-adding amount equally divided into three times and NaHCO 3 at 16.8 g / L. Algae Yield was a remarkable correlation with OD 560 and floating rate by linear regression analysis. There was a corresponding relationship between effects of the four factors on algae yield and on OD 560, floating rate too. In conclusion, OD 560 and floating rate could be served as yield-forming factors.