In order to promote the efficient enrichment of huperzine A,a new co-culture system (CCS),utilizing the symbiotic relationship between Huperzia serrata and endophytic fungi,was proposed.The optimal culture conditions of the CCS were obtained based on the cell survival rate,callus induction rate and multiplication rate.Huperzine A and ergosterol were applied as indicators to control the proportion of botanical cells and endophytic fungi.The growth balance between botanical cells and endophytic fungi was maintained for the optimal time of subculturing.The results showed that the best culture conditions for CCS was:100 Lux Luminous level,95% humidity,MS liquid medium,20.0 g/L sucrose,5.0 mg/L 2,4-dichlorophenoxyacetic acid and 1.0 mg/L kinetin.The 4th day was the optimal subculturing time with the highest concentration of huperzine A,which increased by 49.34% compared with the huperzine A level on the 1st day.The growth of endophytic fungal had a positive effect on the enrichment of huperzine A when the concentration ratio of huperzine A to ergosterol was kept between 1.5 and 2.2.This study provides a new proposal to increase the production of huperzine A with high efficiency and low cost,which can effectively solve the problem of insufficient drug source and has a good application prospect.