Polycyclic aromatic hydrocarbons (PAHs) are a group of organic compounds mainly from incomplete combustion and pyrogenic decomposition. High-molecular-weight (HMW, 4–6 rings) PAHs usually have carcinogenic toxicity and tend to exist in the particulate phase. In this study, daily PM2.5 samples were collected and 16 priority PAHs were detected for one year in the urban district of Beijing, China. Three sources were identified by the positive matrix factorization model (PMF) model: vehicle emission, coal combustion, and petroleum volatilization, natural gas and biomass combustion. With the increase in PM2.5 concentration, the mass contribution of coal combustion and vehicle emission increased; while the mass contribution of petroleum volatilization, natural gas and biomass combustion decreased. The source-attributed cancer risk was further evaluated by Ba Pequivalent concentrations (BaPeq) and source profiles as a result of 30 years of exposure for local residents. Furthermore, contribution to the QALYs (quality adjusted life years) lost by those suffering from lung cancer was estimated for each source. Although vehicle emissions contributed only 50.5% of the mass concentration of PM2.5-bound PAHs, it induced 66.3% QALYs lost (338.9 QALYs). Therefore, the source-attributed QALYs lost was suggested as a better index for the determination of priority control sources rather than the source-attributed mass contribution, in view of protecting human health.