In order to support the potential of achieving long-term improvement of air quality in China, the Energy Foundation China supports Tsinghua University to conduct a study on How to Reach Air Quality Standard of PM2.5 in China by 2030. Based on the results from energy forecasting model, emission inventory, and air-quality model, this report provides recommendations for the major cities of China to reach Air Quality Standard of PM2.5 in near future. The report concludes that further optimization of energy structure is essential to ensure that all 74 major cities in China reach the air quality standard in 2030. In addition, this report also indicates that CO2 emission of China would reach its peak before 2030 if energy structure is deeply optimized. This would suggest that improvement in air quality and reduction in greenhouse gas (GHG) emissions can be achieved simultaneously. This the first report in related field that applies quantitative numerical simulation model to investigate the national air quality and co-control of GHG reductions in future decades.