The bioretention system of low impact development (LID) is an important measure in the purification of urban surface runoff. As refractory organic pollutant, polycyclic aromatic hydrocarbon (PAHs) is one of the important components in urban stormwater runoff.By summarizing the contamination status of PAHs and research progress in the PAHs removal by bioretention system, the paper systematically analyzed the mechanism, effect and impact factors of PAHs removal. The result indicated that the bioretention system removes PAHs by main ways of adsorption, microbial degradation, plant uptake, and volatilization, etc. with the average removal rate of 30%~90%.The factors affecting the removal efficiency mainly include the nature of PAHs, system composition and design, microbial community and environmental factor.The paper suggested to focus on the PAHs accumulation and long-term operation of bioretention system and carry out further study on system optimization and mechanism.