A complete numerical model was developed for the dust removal process in the two-stage electrostatic precipitator (ESP). Numerical simulation method was used to study velocity distribution, particle charging characteristics, particle moving tracks and other physical processes which were difficult to measure directly. The electric field was analyzed using Poisson equation, current continuity equation and homogeneous electric field equation. Fluid flow was elucidated using N-S equation and the standard k-ε turbulent model. Particle tracks were described using Lagrangian method. The accuracy of the numerical model was verified by comparing the numerical results with the experimental data of the cross-sectional velocity and the particle removal rate. Numerical simulation results showed that the fluid flow distribution in two-stage ESP was sensitive to the inlet wind speed. The proportion of charge with different charging methods was determined by particle diameter. And the particles of different sizes had different dominant charging methods. Moreover, the approach of particles to plates was caused by the interaction of the electric force and the drag force in pre-charger, while the approach in dust collection part was dominated by electric force. It was also found that the inlet velocity influenced the particle tracks by changing particle advance speed and internal flow field.