The ultrastructure of the pollen in the Glycyrrhiza uralensis F., Glycyrrhiza glabra L., and Glycyrrhiza inflata Batal. was observed by the scanning electron microscope (SEM). The pollination way, the pollen viability and the stigma activity, the fertilization time ascertainment after pollination were observed by the fluorescence microscope. The results showed that the study on the ultrastructure of pollen offered certain morphology basis for the discrimination of the liquorice. The pollination way of the liquorice was cleistogamy. The pollen viability was the highest at 12:00 in daytime, and the stigma had no ability to accept the pollen exceeding four days after artificial emasculation. The pollen tube entered into the ovule to fertilize 6h after pollination when the fixed pistils were observed different time after pollination. In order to establish the correct strategy of seed selection and breeding of the liquorice in the future, the sexual reproduction properties of the liquorice was studied in the study.