Abstract: As the only raw material for coke production, coking coal supports the stable development of the iron and steel industry. However, China’s natural coking coal resources are nearly depleted, making it difficult to support the high-quality development of the iron and steel industry. Preparing artificial coking coal by hydrogenating and viscosifying other coal species with abundant reserves is expected to solve the above problem. Based on this, a BMIMCl/FeCl₂ liquid catalyst was constructed to study the effect of the BMIMCl/FeCl₂ liquid catalyst on the hydrogenation and viscosity enhancement of a lean coal from Shanxi. The mechanism of the catalyst was hypothesized in conjunction with the characterization results. The results showed that the BMIMCl/FeCl₂ liquid catalyst was used to increase the bonding index of artificial coking coal to 65 and the yield of artificial coking coal to 98.78% at 370 ℃ and a hydrogen pressure of 2 MPa. The bonding index of the artificial coking coal remained around 60 after six cycles of the catalyst, and the liquid phase recovery was 99.12%. Compared to raw coal, artificial coking coal has an increase in aliphatic hydrogen, a decrease in oxygen-containing functional groups, and substantial increase in bonding. The samples before and after hydrogenation were analyzed by various characterization methods. It was found that the liquid catalyst was well-dispersed and stable, and the iron ions in the liquid phase were mainly in the state of Fe³⁺, which had a stronger electronegativity. In addition, GC-MS analysis showed that the hydrogen consumption in tetralin had a positive correlation with the change in the bonding of artificial coking coal. Using DFT and CDD, the adsorption capacity of the C₂ site for hydrogen radicals in the liquid catalyst was calculated. It was found that the adsorption energy of the C₂ site on the imidazole ring for hydrogen radicals was −1.70688 eV, which was lower than the dissociation energy of the α-site hydrogen radicals in tetralin. This proved that the C₂ site was the active center of the catalyst. The mechanism of the catalyst is hypothesized as follows: BMIMCl/FeCl₂ enhances the supply of hydrogen radicals and induces coal pyrolysis radical fragments to combine with hydrogen radicals, preventing the over-hydrogenation of coal pyrolysis radical fragments, which would fragment into small molecular fragments, thus realizing the precise control of the degree of coal hydrogenation.