Some poisonous gases, like H₂S, benzene and toluene, will be produced in the process of in situ shale-oil extraction. These gases may leak out through the flange interface, the pipeline breakage, the geological crack and the outer side of an abandoned well. In this study, the risk of the air environment is assessed and evaluated in the in-situ shale-oil extraction in a country of Jilin Province, China. The most credible accident consequences are calculated at the same time. It is shown that, after leakage from the flange interface or the pipeline or after rupture, H₂S tends exceed the maximum allowable concentration in the workshop in the plant area. The concentration values of H₂S, benzene and toluene exceed the occupation contact limiting values when the wind speed is 2m/s. The concentrations of H₂S and benzene exceed the value of the immediate danger to life and the health concentration limitation. Toluene value is within the standard. H₂S concentrations exceed the limit value of acute poisoning phenomenon, while those of benzene and toluene are within the standard. The plant area is mainly affected during the short time of the leakage accident occurring. According to the risk calculation and evaluation in this study, the project risk level is lower than the same industry standard. The environmental risk is acceptable. In order to minimize the probability of the accident risk and the impact on the surrounding environment, we put forward some prevention and management suggestions.