Four typical pretreatment methods of dilute acid, hydrothermal treatment, ionic liquid and steam blasting were used to treat licorice residue. The effects of different pretreatment methods on sugar production and structure of licorice residue were compared by high performance liquid chromatography, scanning electron microscope, fourier transform infrared spectrometer and X-ray diffraction analysis. The results showed that ionic liquid pretreatment had obvious effect on cellulose in licorice residue, and the contents of glucose, xylose and xylodisaccharide in the enzymatic hydrolysate were the highest, and the enzymolysis rate reached 77.08%±2.12%, which was 2.05 times than that of untreated enzymatic hydrolysis rate. Hydrothermal pretreatment had obvious effects on hemicellulose licorice residue, and the contents of xylose, arabinose and xylodisaccharide in the pretreatment solution were the highest. The enzymatic hydrolysis efficiency of hemicellulum was the highest, reaching 82.37%±1.13%, which was 8.90 times than that of untreated enzymolysis. Steam blasting pretreatment had obvious effect on licorice residue lignin, and the glucose yield in the pretreatment solution was the highest. The structural analysis results were consistent with the component analysis results. Compared with other pretreatment, the lignocellulose structure of licorice residue was effectively broken in the ionic liquid pretreatment process, which was more conducive to the further high-value utilization of licorice residue.