PM₁₀ mass concentration variations in the Yangtze River Delta Region and the causes were investigated, using measurement of PM₁₀ mass concentration and meteorology during 2010~2015 at the regional representative Lin'an Regional Atmosphere Background Station. The results show that PM₁₀mass concentration met the Grade 2 Standard specified in the Ambient Air Quality Standards (GB3096-2012) for 96.17% during 2010~2015. Diurnal PM₁₀ mass concentration showed the maximum value at 09:00 and 20:00, minimum at 06:00 and 13:00, and it also presented a "weekend effect" with higher value on weekend than on weekdays. Monthly variation showed the lowest PM₁₀ mass concentration in July in summer and the highest in January, which negatively correlated with visibility. Annual average of PM₁₀ mass concentration at Lin'an decreased from 79μg/m³ to 56μg/m³ from 2010 to 2015, which is a moderate concentration level in China. PM₁₀ mass concentration correlated well with relative humidity, daily precipitation and local air pressure. Stronger wind also had greater impact on PM₁₀ mass concentration. Back-trajectories and cluster analysis reveal that prevailing air masses were from the northwest and the north in spring, autumn, and winter, and from the sea and the coastal areas in the east in summer. Throughout the years, the dominant air masses were from the north, followed by southerly and east marine air masses. It is concluded that the majority air mass at Lin'an arrived from Anhui, Zhejiang, Jiangsu, Guangdong, Fujian and the north region. Potential source contribution function (PSCF) results suggest that PM₁₀ pollution may mainly originate from the areas around the Yangtze River Delta region, including Shanghai, Anhui, Jiangsu and Zhejiang Provinces.