In order to understand the adaptability of Rhododendron aganniphum var. schizopeplum to strong ultraviolet radiation and alpine environment, we studied the anatomical structures of leaves from nine altitude gradients in Sejila Mountain, Southeastern Tibet by the method of paraffin section. Ten anatomical structure indexes of leaves were measured and analyzed by plasticity index and correlation coefficient. The results showed that: (1) the leaves of R. aganniphum var. schizopeplum were bifacial, the upper epidermis had obvious cuticle, the lower epidermis had trichomes, and the palisade tissue cells had 2-3 layers. (2) As the altitude became higher, the thickness of cuticle, epidermis, palisade tissue, sponge tissue and leaf increased obviously. However, the density and porosity of the tissue structure did not change significantly, and the protuberance of the main vein decreased. (3) The plasticity index showed R. aganniphum var. schizopeplum had lower plasticity, which represented weak adaptability to environment. (4) The indexes were significantly correlated with each other and presented obvious coevolution, except that there were no significant correlations between the thickness of sponge tissue and palisade tissue, between the thickness of lower epidermis and upper cuticle. In summary, R. aganniphum var. schizopeplum adapts to the extreme environment, survives in harsh alpine habitats and becomes a eurytopic species by means of increasing the thickness of cuticle, epidermis, mesophyll and anatomical structure indexes.