Abstract: To study effects of PFK2 on lipid accumulation in microalgae, the phosphofructokinase homologous gene 2 CrPFK2 was cloned, a CrPFK2 RNAi interference vector was constructed and transferred into Chlamydomonas reinhardtii. Measured the biomass and lipid content of the transgenic algal, the growth rate of transgenic algae strain showed an increase in the HSM medium, while it had a decrease in the oil content (by 17.03%-21.48%). The results indicated that the downstream of CrPFK2 expression positively regulated the oil content of the algal cells and CrPFK2 indirectly controlled the oil synthesis of algal cells by changing the photosynthetic carbon flow. These results suggest that CrPFK2 may play an important role in the genetic improvement of microalgae oil.