As an important part of China′s "Going Global" strategy, the construction of "Pan-Asia High-speed Railways" can enhance cross-border cooperation not only between China and Indo-China Peninsula, but also between China and Southeast Asia. Based on aspects of accessibility changes and spatial pattern evolution, this paper explores the influence on spatial relation between border areas of Southwest China and Indo-China Peninsula, which has been brought up by the construction of Pan-Asia High-speed Railways. The results indicate that the construction of Pan-Asia High-speed Railways has generated time-space astringency effect of accessibility both on global and local levels, reduces relative disparity inside the study area to a certain extent, and brings more balance on the degree of transportation convenience along the trunk railways in the study area. It promotes the enhancement of population and GDP service level in the whole region as well, and will lead to a variability from country to country.Relatively speaking, countries with a large population or great economic powers in the research area can have easy access to to the high-speed railways. What′s more, the construction of Pan-Asia High-speed Railways can not only highlight the location advantages of the cities and autonomous prefectures along the railway line, like Kunming city, but also promote regional integration along the mid-route of the line. As a traffic point of connection, Kunming connects China′s western border area and Indo-China Peninsula, links China′s interior heartland and Southeast Asia and even takes up the position as a bridgehead of China′s opening up to the Southeast Asia. Pan-Asia High-speed Railways even strengthen the intensity of spatial relation between the cities and autonomous prefectures in the border area of Southwest China and countries or capital cities in Indo-China Peninsula, especially the ones along the high-speed railways, and it shapes a "^" style pattern of spatial relation, which is an enclosure of Kunming (Qujing)-Bangkok and Kunming (Qujing)-Hanoi. In the end, some targeted suggestions for policy making are provided based on the main research conclusions.