Abstract: The submicron fine particle agglomeration technique is an effective method of blocking and collecting submicron fine dust. In order to simulate dust flow field and particle trajectories in the submicron fine particle agglomeration device, the software Fluent was applied in this test, Lattice Boltzmann model was used to simulate the dust stream flow field, and discrete phase models were used to simulate particle trajectories, the numerical simulation and analysis was carried out for particle trajectories distribution under different inlet velocity and different particle size. The results showed that the vortex generation device in the condensation zone could produce different scale vortex with the speed changing; as the particle size decreasing, the particle was more easily affected by turbulence, the collision probability was greater.