This study monitored the online concentrations ofPM_(1.0),PM_(2.5)and nitrate( NO-3),water-soluble organic carbon( WSOC) and sulfate( SO2-4) in PM_(2.5)in Handan for the first time during December 2014 to February 2015. The results showed that the concentrations ofPM_(1.0)_DRYandPM_(1.0)_WETaccounted for 74. 0% and 81. 4% of PM_(2.5).PM_(1.0)was the major composition of PM_(2.5). Using the method of saw-tooth curve to estimate the source contributions of regional and local sources,the regional sources contr...