Based on the strategic deployment of a country with strong transportation network proposed in the report of the 19^th National Congress of the Communist Party of China，in the context of the rapid development of intelligent technology，intelligent high-speed railway has brought new opportunities for China’s high-speed railway industry. How to design a subsidy mechanism that can achieve mutual benefit between the internal and external systems of intelligent high-speed railway is of great importance. This paper further subdivides the subsidy mechanism into external subsidy mechanism，internal subsidy mechanism and price mechanism. The external subsidy mainly refers to that the government gives enterprises incentives in the form of tax policies and fiscal subsidies on the premise of balancing fairness and efficiency. Given the public welfare of railway transportation services，the internal subsidy is to increase the proportion of social investors’ earning by appropriately expanding the reasonable boundary of the project. This paper first analyzes the theoretical basis of railway public welfare transport service subsidy mechanism，and then summarizes the railway subsidy mechanism of various countries in the world，and compares the main railway subsidy policies of China and Britain，France，Japan and other countries. Combined with China’s current policy status and the characteristics of the public welfare of intelligent high-speed railway，this paper provides enlightenment for the design and construction of subsidy mechanism of intelligent high-speed railway in China.