Abstract: Based on turbulence theory of hydrodynamics, three-dimensional turbulence field equations were established with the use of N-S equation and κ-εmodel to investigate the welding aerosol diffusion process in welded structure workshop. The equations were resolved by the SIMPLE algorithm.The results basically reflected the law of welding aerosol diffusion with the change of space and time.The concentration values of the simulations were basically in agreement with the experimentally measured results of welding aerosol concentration.It was analyzed through the simulations that welding aerosol rose under the acting force of thermal buoyancy and congregated atop workshop, and then diffused along the ceiling with the force of liquid field, and at the same time a part of welding aerosols subsided.When several welding sources were neighbored with each other, welding aerosol concentration increased in parts of the area where the diffusion was superposed.