The chemical composition and antioxidant activity of Prunus avium and the effect of its essential oil on the parameters of ruminal fermentation in sheep have been studied. Chemical analysis of Prunus avium was determined and in vitro fermentation parameters were measured in 100 ml glass syringes for 48 hours to monitor gas production. Prunus avium contains high levels of total fiber (44.44%) and CP (13.85%). The extraction of HE by hydro distillation reveals a low yield. The study of the anti-radical activity shows that the antioxidant activity of the aqueous extract is greater than that of the essential oil. Prunus avium is rich in secondary metabolites (54.35 mg GAE/g DM). For the additive study, there is a significant difference between doses (p<0.01). Increasing the dose of HE can be toxic for the ruminal flora. However, the low dose of 10 µL and 30 µl of essential oil improve in vitro digestibility and therefore the possibility of applying it in vivo.