Aiming at the present situation of the poor performance of an Electrostatic Precipitator (ESP) for fine particle capturing, the theory model and the structure model of a wire - plate ESP are established, PM_2.5 dust removal efficiency under different median particle diameters are numerically simulated using GAMBIT and FLUENT software, and the differences of PM_2.5 capture performance with or without magnetic confinement and ionic wind are compared. The results show that the capture efficiency of the wire - plate ESP for PM_2.5 decreases gradually with the increase of median particle diameter. Both magnetic confinement effect and ionic wind effect can improve the PM_2.5 capture performance to varying degrees, and the combined effect is better. With the increase of median particle diameter, magnetic confinement effect becomes stronger, while ion wind effect becomes weaker. The results can guide the optimization design of ESP in some degree.