Objectives: This study was carried out to evaluate the quality of the peels of various Citrus species. Method: The contents of hesperidin from fruit peels used as Citri Pericarpium such as C. natsudaidai, C. grandis, C. unshiu, and C. sunki, were analyzed by HP-TLC, HPLC, and essential oils of those were analyzed by GC/MS. Results: HPLC analysis showed that the hesperidin from the peel of C. unshiu and C. reticulata was satisfied the standard of Korean Pharmacopoeia. The essential oil was analyzed by GC/MS. As a result, limonene, furfural, 5-methyl-2-furfural, linalool oxide(cis), linalool oxide(trans), terpinen-4-ol, $(-)-{alpha}$-terpineol, germacrene D, 4-methyl-2,6-di-tert-butylphenol was detected in all 4 kinds of Citrus species. Conclusions: As a result of chemotaxonomical similarity analysis with essential oils, the peels of C. natsudaidai and C. grandis are closely related, while C. unshiu is distantly related to the others.