Abstract: In order to explore the optimal concentration and time for mutating Codonopsis pilosula（Franch.） Nannf. seeds, innovate the germplasm resources of Codonopsis pilosula（Franch.） Nannf. and breed new varieties of Codonopsis pilosula（Franch.） Nannf.,the Codonopsis pilosula（Franch.） Nannf. seeds were treated with EMS at different concentrations（0,1%,2%,3%,4%,5%） for 6 h, 8 h, 12 h and 24 h, respectively.The results showed that EMS could inhibit the germination of Codonopsis pilosula（Franch.） Nannf. seeds.And, with the increase of EMS concentration, the germination rate and germination potential of Codonopsis pilosula（Franch.） Nannf. seeds were decreased, the initial germination time and continuous germination time of Codonopsis pilosula（Franch.） Nannf. seeds were prolonged, and the growth of buds was inhibited.In conclusion, 4% EMS treatment for 4 h was the best mutagenesis condition for Codonopsis pilosula（Franch.） Nannf. seeds.