The purpose of this study is to characterize heavy metals in ambient PM10 (particles with aerodynamic diameter below 10 µm) and PM2.5 (particles with aerodynamic diameter below 2.5 µm) particles in a typical integrated iron and steel industry zone (HG) and a background site (ZWY) during February 2011 to January 2012 in the Yangtze River Delta (YRD) region, China. Twelve elements were measured to study their levels, size distribution and sources. At the two sampling sites, Fe was found as the dominated metal in the total detected metals in both particle sizes, followed by Zn and Pb.