To capture the strategic opportunity created by the Belt and Road Initiative to go global, enterprises in China should fully understand the environmental standards of countries and regions along the route. This paper first summarizes the ambient air quality standards of countries along the Belt and Road, and then compares and analyzes these standards in terms of standards setting, pollutants and their limits, regional differences, etc. We found that most countries along the Belt and Road have formulated their own ambient air quality standards; however, there are still profound discrepancies in pollutants setting, average time, and concentration limits among these standards. The standards in Mongolia, Russia, and most Central and Eastern European countries are comparatively stringent, while those in Central and Southeast Asia countries are relatively loose; and there is a great diversity in the strictness of standards in South Asia, West Asia, and Middle East regions. Considering the differences in environmental standards requirement and economic development level, suggestions are proposed accordingly, including environmental standards cooperation, and export of China's environmental standards and industries.