TSP samples and gas phase air samples were collected by an improved high volume active air sampler during domestic heating season in Xi'an, and the concentrations of polycyclic aromatic hydrocarbons (PAHs) were analyzed via GC-MS. The results showed that average concentrations of sigma 16 PAHs in TSP and gas phase were (108.15 +/- 41.44) ng/m3, (260.14 +/- 99.84) ng/m3, respectively. Two and three ring PAHs dominated in the gas phase, while more than four ring PAHs were mainly adsorbed on the particle phase. Good correlation was found between gas-particle partition coefficient and the respective sub-cooled vapor pressures of PAHs. A significant correlation was also found between partition coefficient and temperature, and the regression equation was put forward by stepwise linear regression method. Ratio analysis illustrated that coal burning and vehicle exhaust were the main source of PAHs in Xi' an. Contribution of each source was calculated by factor analysis and multiple linear regression. Partial correlation analysis was applied to study the relationship between air pollution indexes and some representative PAHs of individual factors, which indicated some PAH had same source to SO2 and NO2.