Abstract: The denitrification process involves the removal of reactive nitrogen from stratospheric air masses through the gravitational sedimentation of nitric acid trihydrate particles in polar stratospheric clouds. This process delays the deactivation of reactive chlorine, thereby prolonging the duration of spring ozone depletion and intensifying its magnitude. Using the three-dimensional atmospheric chemical transport model SLIMCAT with different denitrification schemes, numerical simulation study is conducted on two distinct Arctic stratospheric ozone depletion events occurring from December 2010 to March 2011 and from December 2019 to March 2020. Through comparison of the simulation data with observations from the microwave limb sounder (MLS), the denitrification processes during these two events are thoroughly analyzed, and the model's capability to simulate stratospheric chemical composition and denitrification under different schemes is comprehensively evaluated. Results show that, compared to the thermodynamic equilibrium scheme, SLIMCAT model incorporating the Denitrification by Lagrangian Particle Sedimentation (DLAPSE) scheme, which considers microphysical processes, yields a more accurate representation of denitrification in the lower Arctic stratosphere. During both ozone depletion events, the simulated volume mixing ratio of HNO₃ on 456 K isentropic surface in the Arctic region is lower under the thermodynamic equilibrium scheme than under DLAPSE scheme, with an average relative difference of approximately -11%. Consistently, the simulated ClO volume mixing ratio in March is about 10% higher, while O₃ volume mixing ratio is about 4% lower. These results indicate that the thermodynamic equilibrium scheme overestimates the denitrification process in the lower stratosphere, which in turn delays the deactivation of ClO_x. It leads to an overestimation of ClO_x volume mixing ratio and consequently an overestimation of O₃ depletion in the Arctic stratosphere. As the temperature in the Arctic winter stratosphere decreases, HNO₃ volume mixing ratio simulated by the thermodynamic equilibrium scheme initially increases and then decreases, with the transition occurring at a higher critical temperature than in DLAPSE scheme. This leads to the sedimentation of nitric acid trihydrate particles starting at relatively higher temperatures during the cooling process, resulting in greater removal of HNO₃. This phenomenon may explain the overestimation of denitrification in the lower Arctic stratosphere by the thermodynamic equilibrium scheme. Compared to the period from December 2010 to March 2011, the Arctic stratospheric polar vortex from December 2019 to March 2020 exhibits greater stability and intensity, along with more persistent low temperatures. These favorable conditions facilitate the earlier formation and sustained sedimentation of larger nitric acid trihydrate particles in the polar stratosphere, leading to enhanced HNO₃ removal and consequently stronger denitrification in the lower stratosphere during the latter period. The findings of this study contribute significantly to improving the simulation of polar stratospheric clouds and ozone in chemical transport models.