The roots and stolons of some Glycyrrhiza species are used worldwide for traditional folk medicines and commercial pharmaceuticals. Phenolic constituents such as flavonoids and coumarins are medicinal and vary according to species. Therefore, species identification is important for quality analysis. In order to identify Glycyrrhiza species by chemical fingerprinting, methanol extracts of the root bark of Glycyrrhiza uralensis Fischer and G. glabra Limb were analyzed using EI-MS. Differences in kinds and quantity of components are reflected in complex EI-MS data and determining characteristic peaks for each species is straightforward. The characteristic peaks were determined statistically by volcano plot, a multivariate analysis method. EI-MS data of G. uralensis and G. glabra showed differential patterns, and the notable peaks in each pattern were identified. Peaks at m/z 153 and 221 are signature peaks of G. uralensis, and at m/z 173, 309, and 324 are those of G. glabra. In conclusion, we found species-specific patterns by EI-MS that distinguish G. uralensis and G. glabra. This method based on chemical constituent patterns can be applied to identify other Glycyrrhiza species and similar natural products.