Based on the basic theory of transportation geography and GIS technology,a space barrier accessibility model of inter-provincial boundary mountain area is constructed. A case of 42 towns in inter-provincial boundary mountain area of Sichuan,Guizhou and Yunnan is analysed. Accessibility of inside area showed significant characteristics of center periphery of diminishing the spatial pattern. Accessibility of outside area showed significant characteristics of differentiation pattern. The overall level of integrated transport accessibility in Wumeng mountainous areas is low,and the accessibility level of center town is relatively better,accessibility level showed obvious characteristics of low balance,comprehensive transportation accessibility presents structure characteristic ofcoreperiphery layers of differentiation and the differentiation between eastern and western. Finally proposals are put forward such as pay attention to the inter-provincial boundary mountain area transportation networks construction from inter-provincial boundary mountain area transportation network cooperation,construction of rapid transit network channel,regional transportation network unicom rate and global change in the way of transportation,etc.