Abstract: In this article,the purification of bio-hydrogen by microalgae was mainly studied. Bio-hydrogen was obtained from photosynthetic bio-hydrogen production of straw biomass. Domesticated microalgae was used to purify bio-hydrogen in photosynthetic biohydrogen production. Taking hydrogen concentration,carbon dioxide concentration and microalgae biomass as indicators,the effects of initial pH and aeration rate on the deposition of bio-hydrogen were explored,and the bio-hydrogen purification process in photosynthetic bio-hydrogen production by microalgae was optimized to achieve efficient purification and purification of hydrogen. The results showed that the pH value in a certain range had no significant effect on the purification of bio-hydrogen by microalgae. The rate of introducing bio-hydrogen has a significant impact on the growth of microalgae and the purification of bio-hydrogen. When the rotation speed of the air circulation pump is 1000 r/min,the growth of microalgae was the best,and the purification effect on bio-hydrogen was the best,with the maximum biomass reaching 3.68 g/L.