Abstract: To determine the particle initial charge distribution in calculating bipolar agglomeration, this article first solved the electrohydrodynamic flow in electrostatic agglomerator using FORTRAN code. Then, a mass of representative particles with a certain diameter was tracked in the charging zone, and the charge distribution was statistically obtained at the outlet of the charging zone (i.e. the inlet of the agglomerating zone). The presented calculation shows that the particle initial charge distribution is similar to a lognormal function, and that the higher applied voltage and lower inlet velocity, the more particle average charge number.