The invention discloses a method for preparing high-calorific-value alkanes by using an ionic liquid to catalyze deoxygenation in hydrodeoxygenation process of a lignin derivative aromatic compound. According to the method, a negative ion is selected as a proton type ionic liquid catalyst of trifluoromethanesulfonic acid, under the conditions that the temperature is 100-150 DEG C, the hydrogen pressure is 1-5 MPa, and the time is 2-20 hours, the high-efficiency deoxygenation process of a lignin derivative aromatic compound is catalyzed by the ionic liquid in a batch kettle, so that biomass alkane gasoline can be efficiently prepared. According to the method, the reaction conditions are mild, the energy consumption is low, the heat stability of the catalyst is good, the selectivity of product cycloparaffin is high, the conversion rate of the lignin derivative reaches 100%, and the selectivity of the product cycloparaffin is up to more than 98%. According to the method, the addition of protonic acid in a conventional catalytic system is avoided, the low pressure of the reaction system is ensured by the low vapor pressure of the ionic liquid, and the requirement for equipment is reduced. Meanwhile, the ionic liquid used in the process is easy to separate from the product, and the catalytic system is good in cycle performance and has good industrial application potential.