Abstract:The method of extraction, isolation, purification and identification of the neutral and acid inhibitors in the seeds of Kalopanax Septemlobus was given. It is proved that the neutral inhibitor is coumarin, the acid inhibitor is abscisic acid (ABA) by means of paper chromatograph, thin layer chromatograph, high performance liquid chromatograph (HPLC), color reaction and bioassay. The neutral inhibitor can strongly inhibite not only the seed germination of Brassica Chinensis and the radical elongation, but also that of the seed of Kalopanax septemlobus. The study showed that ABA and coumarin exist in the seed coat, endosperm and pericarp of the Kalopanax Septemlobus seed. Both ABA and coumarin can transport from seed cover (pericarp, seed coat)to the interior (endosperm, embryo) as the seeds were stored in refrigerator. In addition, the different results of extracting neutral inhibitor with water, methanol, and alcohol were compared in this paper.