In the event of a severe accident at a nuclear power plant, many radioactive aerosols will be dispersed in the containment. Aerosols can leak into the environment through tiny gaps in the containment vessel. In the early nuclear safety analysis, researchers often ignore the retention of aerosol particles in the tiny channels, resulting in an overly conservative analysis of radioactive source terms. It has been shown that aerosol deposition occurs due to various mechanisms, which have a significant removal effect on aerosol particles. In this study, numerical simulation has been used to study the aerosol deposition patterns and laws in the micro-channel. The effects of particle deposition time, aerosol particle size, and Reynolds number of carrier gas on the deposition rate of aerosol particles are analyzed based on OpenFOAM. The results show that: The particle deposition rate increases as the particle size increases. As the Reynolds number of the carrier gas increases, the particle deposition rate decreases. When the Reynolds number increases from 200 to 7500, the total particle deposition rate drops from 94.3 to 14.8%. In laminar flow, the main mechanism of aerosol deposition is gravitational settling, while in turbulent flow, the turbulent diffusion has a significant effect on the particle deposition. The particle deposition rate increases with particle size but decreases with increasing Reynolds number.