Abstract: Oil shale is a kind of unconventional oil and gas resource. Nevertheless, the solid waste produced in oil shale retorting caused groundwater pollution when accumulated for a long term. In this experiment, backfill (oil shale retorting solid waste) from Fushun West Open-pit was taken as the research object, under the simulated Fushun precipitation condition, to explore the characteristics of pH, conductivity, SO₄^2-, NO₃^- in the process of leaching oil shale retort waste residue. The results showed that under acidic condition, the leaching concentration of Ni and Fe in the waste residue exceeded the class Ⅲ in drinking standard specified in the Groundwater Quality Standard (GB/T 14848-2017), which would have a certain impact on the surrounding environment. Moreover, due to plenty of basic oxides, acid oxides and organic matters, oil shale retorting waste residue had strong pH buffer capacity. However, after 5 days of leaching, the pH value dropped sharply to 5.5, which probably caused by the fermentation and decomposition of organic matters in the waste residue to produce small molecular acids. In addition, the dissolution regulation of NO₃^- had obvious specificity. During leaching process, with the extension of time, the concentration of NO₃^- gradually decreased under acidic and neutral conditions; while in leaching process, the concentration of NO₃^- gradually increased to 600 mg/L, and high concentration of NO₂^- appeared. Due to the anoxic/anaerobic condition of leaching, denitrifying bacteria and other microorganisms in oil shale retorting waste residue might reduce NO₃^-. Under the action of ammoniating bacteria, nitrite bacteria and nitrate bacteria, organic nitrogen could be gradually oxidized to NH₄⁺, NO₂^- and NO₃^-, which led to the accumulation of NO₂^- and NO₃^-. Therefore, the dissolution of harmful substances could be reduced by controlling the redox environment of oil shale retorting waste residue.