Under the background of the global “carbon neutrality” goal, it is of great significance to study the environmental effect of FDI in rapid economic development. This paper proposes an original framework to determine the relative influence of five factors on the Belt and Road countries with a strong FDI-CO₂ association. Based on the panel smooth transition regression (PSTR) model, we establish country-specific and time-specific FDI-CO₂ coefficients for 59 Belt and Road countries during 2003–2018. These coefficients are assumed to change smoothly as a function of five threshold variables, considered the most important in the literature devoted to the FDI-CO₂ correlations. The results show that the degree of GDP per capita, industrialization, openness, and total factor productivity significantly influences the FDI-CO₂ relationship. However, they showed obvious heterogeneity. The coefficient of elasticity of the environmental effects of FDI smoothly transitions between the different intervals, the relationship between GDP per capita and FDI-CO₂ coefficient shows a bell-shaped change, the relationship between degree of trade openness and FDI-CO₂ coefficient also shows a bell-shaped change, the relationship between industrialization level and FDI-CO₂ coefficient shows an inverted N-shaped change, the change of a country’s technological level shows a bell-shaped relationship with the FDI-CO₂ coefficient. The results indicate that PSTR model can be used to study the threshold effect on FDI’s influence on carbon dioxide emissions and the individual and time differences in coefficients of elasticity, to provide a new research perspective and new conclusions on the environmental effect of FDI in rapid economic development.

International student education in China is an important aspect of the Belt and Road Initiative (bri) construction, as well as a beginning point for enhancing the internationalization level of education. China has become the world’s top ten recipients of international students, and its worldwide influence on education is increasing. This research investigates the factors that influence the scale of international students in China and the impact of the bri on education by employing the “Push-Pull Theory”. In particular, we find that joining the bri will significantly increase a country’s student scale in China, both for degree and non-degree education. This effect is especially noticeable in the African region, as well as in middle- and low-income countries. These empirical findings support policy implications for international student education in China.