Abstract: The heavy industrial city is an important source of polycyclic aromatic hydrocarbons (PAHs) pollution. PAHs can exist in karst environment for a long time due to its unique underground space structure, which harms the karst ecosystem and human health. In order to reveal the characteristics of PAHs pollution in karst underground river in heavy industrial city, the researchers in this paper collected 6 sampling sites in Jila underground river pipeline strike in June (wet season) and December (dry season) in 2015, and added 1 sampling site in Xiangshui River during dry season. The results are as follows. ① The average concentrations of ΣPAHs in groundwater in wet reason and dry season were 267.32 ng/L and 350.59 ng/L, respectively. The PAHs were mainly composed of 2~3 rings in wet season and 4 rings in dry season, which were influenced by rainfall and physicochemical properties of each component. ② Jila underground river was affected by Liubei heavy industry, and its PAHs pollution level was medium. ③ The results of health risk assessment showed that only part of the risk index in dry season was higher than 5.0×10^-5, especially in the early childhood stage, indicating that PAHs had certain harm to the residents' health, but the harm was not great. ④ Through the follow-up tracking of PAHs in Jila underground river, it was found that the PAHs concentration in Jila underground river was in a relatively stable state in recent years. The environmental behavior research of PAHs in the multi-environmental media of heavy industrial cities and prevention of PAHs pollution to karst environment is not only an important content of environmental science research, but also provides scientific and technological support for industrial layout and urban planning in karst areas.