To explore a green, efficient and low-energy method for extracting essential oil from Ledum palustre L., the enzyme-assisted water vapor distillation method was used to extract essential oil, and the chemical composition was analyzed and compared with the conventional water vapor distillation method by gas chromatography-mass spectrometry, and the antioxidant activity of essential oil was studied as well. The results showed that the optimal process conditions of the enzyme-assisted water vapor distillation method are as follows: the material-to-liquid ratio is 1∶20 g/mL, the pH of the enzyme is 5.5,the enzymolysis time is 4 h, the enzymolysis temperature is 55 ℃, the concentration of the enzyme is 1.5%, and the extraction time is 1.5 h. Under this condition, the extraction rate of essential oil from L. palustre is 1.71%. Compared with water vapor distillation, the extraction rate of essential oil increased by 67.65%. There are 53 kinds of chemical components of essential oil from L. palustre obtained by enzyme-assisted extraction, and only 44 kinds of chemical components of essential oils extracted by water vapor distillation method. It is shown that enzymolysis can make the essential oil better released, so that the chemical composition of the enzyme-assisted extraction of essential oil is abundant. In the antioxidant experiment, the essential oil extracted by enzyme assisted extraction had stronger scavenging ability on DPPH free radical, ABTS free radical and hydroxyl free radical than the essential oil extracted by steam distillation. In general, the essential oil extracted by enzyme assisted extraction had obvious antioxidant activity and a good dose-response relationship. This study will provide reliable process parameters for the large-scale production of essential oil, and provide basic data and reference for evaluating its antioxidation.