Abstract: In order to ensure the safety of reactor operation, the continuous monitoring of aerosol particles is needed. Aerosol particles transport and deposit in cracks. In this paper, the transport and deposition of aerosol particles at low Reynolds number are obtained by numerical simulation. It is found that the transport of aerosol particles in cracks is affected by the air velocity, particles size, crack size and other factors. At low Reynolds number, the maximum particle size of aerosol particles that can penetrate 0.5 mm cracks decreases continuously. When the particle size is larger than 600 nm, the deposition of aerosol particles are more affected by gravity. The penetration rate of aerosol particles decreases with the increase of particle size. When the particle size is 600 nm, it reaches the maximum and the penetration rate is close to 100%. When the particle size is less than 600 nm, the penetration rate of aerosol particles decreases with the decrease of particle size. Considering the size of particles and straight cracks, the narrow degree of aerosol particles which can reach the maximum penetration rate in long straight cracks is 0.15%.