<p>To investigate the interaction mechanism between particles and airflow during shot peening, the computational fluid dynamics (CFD) method was employed to study the aerodynamic characteristics with a B-type nozzle. The drag model was used to describe the interaction between particles and airflow, and the motion laws of particles were examined and then verified by the particle tracking velocimetry (PTV) method. The results show that the simulation results of particle motion agree with the experimental findings. The airflow velocity decreases from supersonic in the nozzle to subsonic outside the nozzle through a series of complex shock waves, forming an obvious impact diamond which leads to the spatial scattering of the particles outside the nozzle. The velocity and spatial distribution of particles are significantly influenced by the nozzle structure, due to the expansion and acceleration of airflow were predominantly occurred in the nozzle. The maximum velocity of 0.36 mm diameter steel shots can reach 64.3 m/s with an inlet air pressure of 6 atm. The empirical formula for predicting particle velocity can estimate the maximum velocity of particles during shot peening, but it fails to capture the dispersion characteristics accurately and lacks precision in its predictions. The effectiveness and accuracy of simulation in obtaining aerodynamic and particle motion characteristics have been demonstrated, thereby facilitating the optimization of nozzle structure.</p>