Abstract: In order to optimize the reasonable spray gun layout of circulating fluidized bed semi-dry desulfurization and denitrification reactor, the circulating fluidized bed simultaneous desulfurization and denitrification tower of a thermal power plant was taken as the original object in this paper, and the high pressure water spray gun layout in the reactor was simulated. Through simulation and comparison of results, a more suitable spray gun layout was obtained. The optimum setting of spray guns was 4 with circular arrangement. The advisable distance of the spray gun inserted into the tower was 0.5~0.7 m. The maximum droplet size of the spray was less than 150 μm, which was conducive to the uniform distribution within the reactor and the complete evaporation of the droplet, achieving smooth and stable running of circulating fluidized bed semi-dry reactor,as well as high efficiency desulfurization and denitrification.