Abstract: In order to know location of inhibitory substances in Davidia involucrata seeds and changes of inhibitory activity during stratification, activities of extracting solutions of D. involucrata seeds were studied after stratification for 12 and 16 months. Extracting solutions of endocarps, seed endosperms and embryos(kernel)in D. involucrata were prepared by using methanol and acetone as extracting solvents. The results indicated that germination inhibitors existed in both kernel and endocarp of D. involucrata and with the increase of concentration of extracting solutions, activities of inhibitors increased too. But the inhibitory activities of kernel extracting solution were significantly higher than that of endocarp extracting solution. Besides, methanol extracting solution of seed kernel was at a higher level of inhibitory activities than that of acetone extracting solution, while no significant difference was presented in endocarps by the two extracting solutions. The inhibitory activities in seeds were decreased markedly after cold stratification for 12 months and then variable temperature stratification for 4 months. However, at this moment, germination index of cabbage seeds treated with 0.09 g/mL methanol extracting solution of seed kernel was still significantly inhibited, which indicated that some inhibitors in D. involucrate seed kernel remained strong inhibitory activity after stratification for 16 months.