Abstract: A fossil leaf of Machilus leptophylla and a fossil leaf of Machilus cf. longipedicellata were collected from the Pliocene Mangbang Formation in Tengchong, Yunnan Province. Their architectural and epidermal characteristics were investigated by laboratory observation and cuticular analysis, and were compared with their living relative species. These two fossil leaves are oblong, coriaceous. Their primary veins are straight and moderately thick, and their secondary veins are pinnate. However,epidermal structure of the Lauraceae is very typical, the subsidiary cells are brachyparacytic and the guard cells are located underthe two lateral subsidiary cells. The trichome bases of these two fossil leaves are unisetose. Therefore, the cuticles of two fossil leaves are considered to belong to the Machilus based on the detailed comparison of leaf architecture and epidermal structure.The results show that both leaf architectural and epidermal characteristics of the fossils are very similar to the living features and thus the combined usage of leaf architecture and cuticle in fossil classification and identification can yield more reliable results than solely used. The convincing identification has undoubtedly enriched the fossil records of Lauraceae in China. In addition,the stomatal density (SD) and the stomatal index (SI) have been calculated for these fossils and are compared with their living species. The results imply that leaves of fossil Machilus leptophylla and fossil Machilus cf. longipedicellata may have the potential to be used as indicators of palaeoatmospheric CO2 concentration. Through comparing the stomatal ratios of the modern Machilus leptophylla and Machilus longipedicellata (the living relative species of these two fossil leaves) to the fossil species, indicate that the CO2 concentration in the Pliocene is much higher than that of today. Our analysis suggests that the Neogene climate in western Yunnan might be warmer and more humid than the current condition.