The invention relates to a gas desulfurization system which comprises an alkaline bath, a desulfurization tower, a circulation pump and a metering pump, wherein an alkaline feeding pipe is connected inside the alkaline bath, the alkaline bath is an alkaline liquor circulation bath, the circulation pump and the metering pump are arranged between the alkaline bath and the desulfurization tower, alkaline liquor flows into the circulation pump through the metering pump, the circulation pump is used for conveying the alkaline liquor in the alkaline bath to the top of the desulfurization tower, and a bypass pipe is arranged on an alkaline liquor feeding pipe of the desulfurization tower. The gas desulfurization system is remarkable in effect, superior to the prior art, and suitable for being popularized and used in a large scale.