In order to improve the utilization of lemon peel, the optimal processes for essential oil extraction of lemon peel were studied by Cellulase-Assisted Hydrodistillation(CAHE). Based on the single-factor test, taking the enzyme dosage, solvent to material ratio, enzymolysis time, and distillation time as the influce factors, the response surface methodology was applied to optimize the parameters of extraction. Meanwhile, the volatile composition were determined by GC-MS. Additionally, the microscopic structural changes of sample before and after extraction are observed to understand the characteristics of different extraction methods. The optiaml extracting conditions were as followed: enzymolysis temperature 50 ℃, pH 5.0, enzyme dosage 1.1%, ratio of solvent to material 16∶1 （mL/g）, enzymolysis time 63 min, distillation time 140 min. Under the conditions, the yield of essential oil reached 2.12%. A total of 27 compounds were identified, in which the limonene was the major constituent. Scanning electron microscopy demonstrated that cellulase effectively destroyed the cell structure of lemon peel, which accelerated the release of essential oil. Furthermore, the extraction efficiency of essential oil extracted by CAHE was similar in quantity (yield) and quality(chemical composition) to hydrodistillation, but less time comsuming.