In the present study, a series of wet flue gas desulfurization experiments have been carried out in comparison with different slurry feeding ways, i.e., by series connection and by parallel connection, by means of crossflow scrubbing with falling film. The experiment results show that there is optimal desulfurization performance for the slurry feeding way by series connection. A liquid side mass transfer-reaction model and desulfurization mass transfer by cross-flow scrubbing model have been developed. The pH values of the outlet slurry inside the reactor and the ion concentration distributions of H2SO3, HSO3. and SO₃^2- along the axial direction of the tubes were obtained by analyzing and calculating the models. The calculation values agree well with the experimental values. It shows that the models can predict well the ion concentration distributions along the axial direction of the tubes.