The rapid development of high-speed rail(HSR) and air transport in China has encouraged research on the spatial effects and safety of these two modes of transport, and on the competition between them. We report here an investigation of the effects of competition between HSR and air transport in China from a geographical perspective. The spatial service hinterlands for HSR and air transport accessible within one and two hours by road transport were investigated using a method based on a geographical information system and the overlapping service hinterlands of HSR and air transport were established. A city with both HSR stations and airports, or that was accessible to HSR stations and airports within a certain travel time by road transport, was defined as the overlapping market. The spatial effects of competition between HSR and air transport at present and in the future were then studied with respect to the planned HSR network and airports. The results showed that both HSR and air transport tend to serve areas with high population densities and well-developed economies and in 2012 most of the population and GDP in China were accessible within two hours by road transport to an HSR station or airport. The different technical and economic characteristics of HSR and air transport determine the advantage markets. Spatially, the service hinterland of HSR mainly focuses on urban agglomerations and economic corridors in the eastern and central regions, whereas air transport has a competitive advantage in the more inaccessible western region of China. The overlapping market of HSR and air transport will become increasingly large in the future and cities with a population of over one million and cities within 30 km to both airports and HSR stations will become the major competitive markets. Considering the cost of construction and the number of passengers required for economic operation, as well as the competition with air transport, it is suggested that the construction of some HSR projects in the western region of China should be canceled or slowed down. The rapid development of high-speed rail (HSR) and air transport in China has encouraged research on the spatial effects and safety of these two modes of transport, and on the competition between them. We report here an investigation of the effects of competition between HSR and air transport in China from a geographical perspective. The spatial service hinterlands for HSR and air transport accessible within one and two hours by road transport were investigated using a method based on a geographical information system and the overlapping service hinterlands of HSR and air transport were established. A city with both HSR stations and airports, or that was accessible to HSR stations and airports within a certain travel time by road transport, was defined as the overlapping market. The spatial effects of competition between HSR and air transport at present and in the future were then studied with respect to the planned HSR network and airports. The results showed that both both HSR and air tran sport tend to serve areas with high population densities and well-developed economies and in 2012 most of the population and GDP in China were accessible within two hours by road transport to an HSR station or airport. The different technical and economic characteristics of HSR and air Spatially, the service hinterland of HSR mainly focuses on urban agglomerations and economic corridors in the eastern and central regions, whereas air transport has a competitive advantage in the more inaccessible western region of China. The overlapping market of HSR and air transport will become increasingly large in the future and cities with a population of over one million and cities within 30 km to both airports and hsr stations will become the major competitive markets. , as well as the competition with air transport, it is suggested that the construction of some HSR projects in the western region of China should be canceled or slowed down.