Chlamydomonas reinhardtii-se with longer growth cycle different from other wild strains used broadly before has been chosen in the two-stage photosynthesis and H2 production progress.Using the length of cells' growth cycle,the density of cells and the activity of induced hydrogenase as criteria,the optimal formulation of culture medium was obtained as seTA(se -Tris Acet) which contains acetic acid as C source,higher concentration of N and stronger pH buffer system based on the se formulation.The results also indicate that the pH stability and the concentration of N exert a great influence on the growth of C reinhardtii-se and the acetic acid is the key substance for hydrogenase induction.