Abstract: The ultra-low emission of flue-gas pollutants reformation project on a 600 MW unit adopts gas tower integration technology, bringing the desulfurization tower, the wet electrostatic precipitator and the chimney in one indirect dry cooling tower (the 4-in-1 tower). In this paper, a scheme of ultra-low emission reform is introduced and the finite element method combining with the practical experience is adopted to optimize the 4-in-1 tower layout on the basis of structural calculation and analysis. Comparisons are made between the 3-in-1 scheme and the 4-in-1 one, also between the two different layouts of 4-in-1 tower, from the technological and economic perspectives. The vertical integrated layout for the desulfurization tower, the wet electrostatic precipitator and the chimney is adopted. The original desulfurization tower is reinforced also. The principle and method of the design for the over-limit high temperature elevator are introduced. Application results showed that the environmental protection facilities are working steadily . Operating with high, medium and low load levels and three types of coal quality, the average mass concentration of SO₂ is about 9 mg/m³, and the average mass concentration of dust is about 3.38 mg/m³, demonstrating better benefit in energy saving and environmental protection .