The process layout of 5 kinds of 5 000t/d Wet FGD systems for new and old cement clinker production lines were analyzed and compared. Due to the diversity of the kiln tail process layout in the cement clinker production line, the author puts forward the principles to be followed in the process layout and the key points to be paid attention to in the design of the Wet FGD system. The centralized layout of desulfurization system should be given priority in reconstruction projects. The system layout should shorten the distance between the desulfurizing tower, the preheater chimney and the exhaust fan. At the same time, the layout of the kiln preheater workshop should be considered comprehensively in the new project.