Abstract: Samples from both ambient particulate matter (PM₁₀) and PM10 sources were collected in Wuxi City in 2005. Their inorganic elements, water-solvent ionsand carbon species were analyzed to identify the sources of PM₁₀. Contribution of secondary organic carbon (SOC) to PM₁₀ was determined by the “OC/EC minimum ratio" technique, and the chemical profiles of sources and ambient PM10 were established. Sources of PM₁₀ in Wuxi City were analyzed based onthe chemical mass balance (CMB) receptor model and nested chemical mass balance(NCMB). The results showed that suspended dust was the most important PM10 source with a contribution of 50.49%; flying ash from coal combustion and vehicle exhaust were also important sources with contributions of 13.97% and 7.80%, respectively. Sources like SOC, SO₄^2-, construction cement dust, NO₃^-, soil dust and Ferrous dust were all significant contributive sources toambient PM₁₀. The annual average SOC concentration was 6.94 μg/m³, accounting for 6.18% of the total mass in ambient PM₁₀.