Abstract: To study the micro-morphological characteristics of the leaf epidermis of five species of Ruellioideae（Acanthaceae）, Baphicacanthus cusia, Barleria cristata, Eranthemum pulchellum, Gendarussa vulgaris, Andrographis laxiflora of Ruellioideae（Acanthaceae）, the leaf epidermis were observed by scanning electron microscope（SEM）. The results showed some characteristics are same among five species such as cystoliths and glandular scale in lower epidermis, but G. vulgaris are distinctly different with other four species in characteristics of stomatal and upper epiderinis. This suggests that G. vulgaris should separate from the Ruellioideae. And the difference of leaf epidermal micro-morphological characteristics among five species could provides the new reference to classify and identify the plants of Ruellioideae（Acanthaceae）. There may be a distant relation among Gendarussa and other four genus.