Effect of flowering mode and pollination on reproductive success and interspecific relationship of Glycyrrhiza glabra L.and Glycyrrhiza uralensis Fisch.were studied by flowering phenology observation,pollinator observation,hand-pollination experiments.(1)Their overlapping time of the florescence was 21 days,both G.glabra L.and G.uralensis Fisch demonstrated “concentrate a large number of flowering mode”,but G.uralensis Fisch.was batches gradually flowering.And that have great significance for improve the reproductive success rate,avoid inbreeding depression and maintain the stability of the species.(2)Their pollination insects are different in numbers and varieties,but Coelixys afra Lepeletier,Apis mellifera Linnaeus and Xylocopa valga Gerstaecker pollinate for both of them.(3)The rate of fruitage in crossing combination of “♀G.uralensis×♂G.glabra” was 48.3%,the “♀G.glabra×♂G.uralensis” was 39.4%.This means that hybridization between G.glabra L.and G.uralensis Fisch.are compatible and no reproductive obstacles.Studies have shown that overlapping time of the florescence,common floral visitors and compatible of hybridization may be important conditions to successfully make interspecific pollination and speciation for natural hybrid species of two Glycyrrhiza L.species.