To decrease the bolting rate of Angelica gigas, The growth inhibitors such as MH, Pp333 (paclobutrazol) and CCC(chloroniequat or Cycocel) were treated twice with the interval of 20 days atthe forming stage of flower bud.Growth and bolting rate in plot treated inhibitors were retarded and decreased, and the yield ofroots was also decreased compared with non - treatment. The treatments of MH and Pp333 amongthree inhibitors showed the better effects in decreasing the bolting than that of CCC, but they did notshow the significant in the yield and contents of decursin among each of them.In order to improve the decreasing effects by chemicals, selection of suitable reagents, concentrationand number of treatment should be investigated.