China proposes the Belt and Road Initiative to strengthen the interconnection between China and neighboring countries on the changeable world situation. Studying the neighboring languages, it’s one of the essential ways to strengthen China’s soft power in neighboring countries, especially for the Thai language. However, there is a small number of research papers about China implementing its soft power policy. Therefore, this research paper aims to study why and how China implements Thai language teaching as soft power to increase its influence under the One Belt One Road Initiative. This research is conducted with qualitative research, which is conducted by document analysis. Official documents are analyzed. This research result shows that China strengthens its soft power by popularizing Thai language teaching in two southern provinces of China, namely Yunnan and Guangxi, due to their geographical location which is closed to Thailand. The specific strengthening soft power measure is expanding the Thai language teaching from a few universities to offering the Thai language major or Thai language as the second major in many universities in Yunnan and Guangxi Provinces.