Abstract:Leaf structure of Aquilaria sinensis （Lour.） Gilg （Thymelaeaceae） observed under light microscope shows that the leaves are of typically bifacial exhibiting xeromorphic characters. Epidermis consists of a row of irregular epidermal cells with thick horny layers and are closely arranged. The horny layers in upper epidermis are 1μm thicker than that in lower epidermis. Sunken stomata exist only in lower epidermis which is sparsely covered by unicellular hairs. The stomata are of anomocytic type. Mesophyll is well developed, in which many rectangular lithocyst arranged perpendicularly to the epidermis. Palisade parenchyma is composed of 1-2 layers of cylindrical cells. The cells in outer layer of palisade parenchyma are transformed into idioblasts. In spongy parenchyma there is a layer of hypodermis which is composed of idioblasts. The ratio of the thickness of palisade parenchyma to spongy is 1： 3. The micrib belonging to bicollateral bundle is well developed. The bundle sheath is composed of idioblasts. The leaves are rich in extraxylary fibres. The structural characteristics show that it is a xerophytic species adapted to arid environment.