Abstract: Hydrogenation reaction and hydrogen consumption are essential for efficient and reasonable utilization of hydrogen in refineries. In order to obtain coupling relationship between hydrogen consumption and variation of the process parameters at offdesign conditions, a wax oil hydrotreating unit was simulated by using ASPEN Plus, in which sulfide, nitrides and aromatics were divided into four lumps. The simulation results were verified by operational parameters and properties of feedstock and products of a practical wax oil hydroteating unit. Based on the simulations, the hydrogen consumption of a wax oil hydrotreating unit at different processing loads and sulfur contents of feed oil was calculated and analyzed. The results show that the trend of hydrogen consumption varying with processing load agrees well with the results obtained by empirical correlations. However, when sulfur content of feed oil increases, hydrogen consumptions obtained by simulations are more close to the practical situations. The fundamental data obtained from simulations will provide a deep understanding of calculations on hydrogen consumption of hydrogenation reaction in refineries.