An electrostatic precipitator module and a desulfurization system are capable of easily discharging wash water from a wet electrostatic precipitator module. The electrostatic precipitator module includes an arrangement of discharge electrodes and collecting electrodes alternately disposed and spaced apart from each other, the discharge electrodes configured to be charged to a predetermined voltage for generating a corona discharge between the discharge electrodes and the collecting electrodes; and tie rods for fixing the discharge electrodes and the collecting electrodes. Each collecting electrode has a lower edge inclined downward with respect to the ground. The lower edge of each collecting electrode includes separate lower edge portions respectively inclined downward from opposite side ends of the collecting electrode and a lowermost point at which wash water is concentrated and discharged to a discharge guide installed directly under the lowermost points. The discharge guide has a width substantially smaller than the collecting electrode.