Abstract: Taking the pathogenic of Fusarium oxysporum and F.solani as test materials, the pathogenicity of these two pathogens to three kinds of medicinal licorice root rot was analyzed.Then the effects of aqueous extracts of three kinds of medicinallicoroce′s litters（leaves） on the mycelial growth and sporulation of F.oxysporum and F.solani were detected by the exogenous addition method, in order to explore the mechanism of the frequent occurrence of licorice root rot under continuous cropping condition.The results showed that F.oxysporum and F.solani had strong pathogenicity to the three kinds of medicinal licorices, and could cause typical symptoms of root rot disease.In the concentration range of 0.005-0.020 g·mL^-1,the aqueous extracts of G.glabra and G.uralensis leaves significantly promoted the growth and reproduction of the two pathogens, which significantly increased the colony diameter and spore amount of F.oxysporum by 14.06%,10.58%,24.50% and 48.39%,and significantly increased the colony diameter and spore amount of F.solani by 8.79%,12.25%,17.11% and 25.13%,respectively.The aqueous extract of G.inflata leaves showed the characteristics of low promotion and high inhibition on the mycelial growth and spore production of the two pathogens, and its maximum increased the colony diameter and spore volume of F.oxysporum by 3.63% and 14.86%,which significantly increased the colony diameter and spore volume of F.solani by 6.54% and 16.58%.The order of the influence rate of the aqueous extracts of three kinds of medicinal licorice leaves on the growth and reproduction of two kinds of pathogens was G.uralensis＞G.glabra ＞G.inflata.In conclusion, the large accumulation of leaves of three kinds of medicinal licoriceas litter in the farmland may be the main reasons for the frequent occurrence of root rot of licorice under continuous cropping condition.It is suggested that the licorice leaves should be harvested and removed annually before they turn into yellow and fall off.