Abstract: PM_2.5 samples of winter and summer were measured and WRF-CAMx modeling system was developed to simulate PM_2.5 and secondary inorganic ions in Beijing-Tianjin-Hebei to study pollution characteristics and regional transmission of PM_2.5 in Tangshan, which obtained PM_2.5 chemical components data and estimated the regional contribution to PM_2.5 and secondary inorganic ions. Results indicate the concentration of PM_2.5 are (117.9±56.6) μg/m³ and (77.3±29.8) μg/m³ and have the standard exceeding ratios of 65.0% and 41.7%, total water-soluble ions concentrations are (58.4±17.9) μg/m³ and (42.6±23.6) μg/m³, which account for 49.4% and 55.0% in winter and summer, representing major chemical components of PM_2.5. Cu, Zn, As, Sr, Cd, Sb, Pb mainly come from anthropogenic pollution sources, while the others such as Na, Mg come from crustal sources. The contribution of non-local sources to PM_2.5 was 26.9% and 31.1% in winter and summer respectively. The transmission effect of SIA was more significant compared to PM_2.5. The contribution of non-local sources to PM_2.5 and SIA in summer was higher than that in winter. The contribution of non-local sources had a certain degree of rise during the high concentration process. Stable atmospheric conditions, low wind speed and increasing coal emissions are main causes of heavy pollution process.