Swirl atomizers are commonly used by refining and chemical companies to wash out ammonium chloride deposits. Experiments and numerical simulation were performed to investigate the atomization and mixing characteristics of swirl atomizers. The volume-of-fluid Lagrangian method was applied in the simulation, and its results were compared with experimental data to validate its accuracy. Results demonstrated that the entrainment effect of the airflow changed the atomization angle and coverage area of water. Momentum exchanges between water and airflow promoted the fracture of liquid membranes and formed small droplets.