Anthraquinones present in the leaves of Aloe L. are the main active principle for medical purposes. Therefore, to study their relationship is of great interest to the medical profession. Methods　Leaves of 11 species of Aloe L. were studied by phytotomy, histochemistry and phytochemistry. Results　The structures of the aloe leaves were basically similar as characterized by the presence of the large, well developed parenchymatous cells in the phloem pole where anthraquinones were stored. Some positive correlations exist between the contents of anthroquinones in the leaves of different species and different parts of leaves of the same species, and some phytotomic factors including the density of vascular bundles, the ratio of large parenchymatous cells in phloem and the thickness of the chlorenchyma. Conclusion　Results of the study may provide references during purchasing and for the selection and breeding of new improved species.