We analyzed the plasma chemistry, particle formation and growth in the pulsed corona discharge process(PCDP) to remove NO_x and investigated the effects of several process variables (initial concentrations of NO, NH₃ and H₂O and electron concentration). In the PCDP, most of NO is converted into NO₂ and, later, into HNO₃ which reacts with NH₃ to form NH₄NO₃ particles. As the initial NO concentration increases or as the initial H₂O concentration and the electron concentration decrease, it takes longer reactor length to remove the NO_x. With the increase of initial NO concentration, more NH₃ is consumed to remove the NO initially supplied and NH₃ disappears more quickly in the PCDP. In the beginning of the reactor, the particle concentration and the standard deviation of particle size distribution increase quickly because of fast particle formation from the NO initially supplied. The particle concentration and the standard deviation decrease in the PCDP where the NO initially supplied is all consumed. Later, the particle concentration decreases slowly by the balance of disappearance rate of particles by coagulation and generation rate from the NO newly formed and the NO₂ by N₂O₅ decomposition reaction. New particle formation stops after the NH₃ is all consumed and the particle concentration and the standard deviation drop quickly by coagulation between particles, but the average particle diameter grows quickly. The predicted particle diameter was in close agreement with the published experimental result. The information on the particle characteristics can be the basic raw materials to develop more efficient PCDP and particle collection equipments.