Following the vast development of high-speed railway in domestic, China decided to spread its high-speed railway investment, begin its industrial transition as the creator and the technology innovator. China started to approach Southeast Asia countries which is seen to have the potential market which need to develop. This condition also supported by the high demand of Southeast Asia countries that need high-speed rail technology and the existence of Japan’s Shinkansen technology in the region. For the result of China’s efforts, China was successfully built Indonesia’s Jakarta-Bandung high-speed rail project, China-Laos railway projects, and China-Thailand railway projects. The realization of the projects then become a big question, that China which is likely focus on trading and is only a newcomer for railway technology turn to make efforts on the railway project to defeat the experienced Japanese railway technology and Japan strong ties with Southeast Asia countries. The objective of the thesis is to analyze the reason behind the alteration of China’s political behavior which changed from trading to investment. The qualitative methods was applied, that the writer using media and library research such as official webpage, government webpage, newspaper, journal and prior research related to China, Southeast Asia, ASEAN and railway. The research found that China has considered that the decision of sending railway will bring more advantages for domestic China that it helps the realization of One Belt One Road that have the advantages whether economically or politically.