Abstract: Lemon peel, as a typical carbon solid waste in fruit processing industry, of which efficient recycling and resource utilization contribute to the development of renewable liquid fuel and economic benefits. Citric acid contained in lemon peel has been proved to be a weak acid that can effectively promote the hydrothermal conversion of biomass and its derivatives to produce high value-added furan products. Therefore, sulfuric acid is used to catalyze the hydrolysis of lemon peel to produce precursor of important liquid fuel, such as levulinic acid (LA) and furfural (FF). The promotion effect of common metal salt on catalysis of sulfuric acid to the hydrolysis process of lemon peel is explored. The citric acid contained in lemon peel promotes the hydrolysis process. Combined with catalysis of sulfuric acid, the LA yield as 22.6% can be obtained under the mild hydrolysis conditions of 170 ℃ and 90 min, and the addition of the KCl can effectively inhibit the secondary reaction of the decomposition process of the lemon peel and enhance the interaction of the sulfuric acid and the lemon peel. Compared with AlCl₃ and FeCl₃, the LA yield is increased to 27.9% by the addition of KCl. Preparing conditions of glucose and FF are milder than that of LA. Enhancement of temperature and acidic concentration, and prolonging reaction time all lead to significant decrease in glucose and FF yield.