Abstract: Air pollution is one of the most important factors affecting the solar radiation reaching the earth’s surface under the clear（cloudless）sky conditions. In this work,six typical cities in China with serious pollution are selected:Beijing,Shenyang,Shanghai,Wuhan,Guangzhou and Chengdu. Based on the daily monitoring data of air quality and the daily observation data of surface solar radiation and sunshine hours from January 2014 to December 2020,the relationship between air quality index（AQI）and global and diffuse solar radiation under clear sky condition is quantitatively analyzed. The results show that air pollution will reduce the clearness index,decrease the global solar radiation and increase the diffuse solar radiation. From 2014 to 2020,the total annual attenuation and attenuation rate（7 years in total）of global solar radiation caused by air pollution（AQI＞100）is larger in Beijing（212.40 MJ/m~2,4.01%）,Shenyang（184.16 MJ/m~2,3.00%）,Wuhan（106.36 MJ/m~2,3.04%）and Shanghai（123.80 MJ/m~2,4.37%）,while Chengdu（58.03 MJ/m~2,3.82%）and Guangzhou（18.76 MJ/m~2,0.96%）have smaller attenuation. The total annual increment and increment rate of diffuse solar radiation caused by air pollution（AQI＞100）is respectively 256.64 MJ/m~2and 12.96% in Beijing,134.45 MJ/m~2and7.10% in Shenyang,22.62 MJ/m~2and 1.36% in Wuhan,43.40 MJ/m~2and 9.71% in Chengdu,94.74 MJ/m~2and 8.25% in Shanghai and 37.79 MJ/m~2and 5.90% in Guangzhou.