Abstract: The extraction and decolorization conditions for Spirulina platensis polysaccharides using hot alkali and hydrogen peroxide were investigated, and the process was optimized. Based on the results of a single-factor test, the yield and decolorization rate of polysaccharides were taken as indices to optimize the technological conditions for extracting polysaccharides from Spirulina platensis using the hot alkali method and decolorizing them with hydrogen peroxide using the response surface methodology. The optimal conditions for hot alkali extraction of polysaccharides from Spirulina platensis were determined as follows: NaOH concentration of 1.5%, extraction temperature of 90 ℃, extraction time of 4 hours, and material-to-liquid ratio of 1:20 g/mL. Under these conditions, the yield of polysaccharides from Spirulina platensis was 5.18%±0.23%. The optimal conditions for decolorization using hydrogen peroxide were found to be: 17% hydrogen peroxide solution, decolorization time of 55 minutes, and decolorization temperature of 50 ℃. Under these conditions, the actual decolorization rate was 82.54%±0.03%, and the retention rate of polysaccharides was 83.45%±0.13%. The findings of this study provide valuable insights for the development and utilization of Spirulina platensis polysaccharides.