This paper explores the impact of “The Belt and Road Initiative” language strategic planning on the integration of ethnic societies by analyzing the role of language policy in promoting ethnic understanding, economic cooperation, and cultural exchanges. The paper constructs a theoretical framework for analyzing the impact of language on economic growth, reveals the deep-rooted mechanism of the economic development effect of language capital, and establishes a PVAR model to empirically analyze the language capital effect of China’s OFDI. Empirical testing of the impact of comprehensive linguistic similarity on culture among the Belt and Road countries is done through QAP analysis. The analysis shows that the official languages of each country have a significant promotion effect on OFDI in non-English-speaking countries (P<0.01). The economic growth spillover effects are all greater than 0, indicating that the economic growth rates of countries with similar languages are mutually influential. The combined linguistic similarity between countries plays a significant facilitating effect on cultural flows (p<0.01) and cultural preferences and a hindering effect on high cultural flows (standardized regression coefficient <0).