Coal gasification technology is an effective way to the clean and efficient utilization of coal, the entrained-flow gasification process with radiant syngas cooler (RSC) can effectively recover the sensible heat from high temperature syngas and improve energy utilization rate. The radiation screen adopted inside the RSC is not only keeping the overall structure compact, but improving the heat transfer area greatly. In order to study the thermal deformation of the radiation screen in the RSC under gasification operating conditions, a three-dimensional radiation screen model is established by using the fluid-structure coupling principle to simulation analysis. The simulation results show that under normal operating conditions, the temperature of the whole water-cooling pipe reaches the maximum value at 5.30 m from the top. In the circumferential direction, the surface temperature of the pipe 1 closest to the center of the RSC is parabola distribution. Temperature in the middle of the fire-facing side is the highest, and the maximum temperature difference between the fire-facing side and its back side reaches 60 K. Due to the cooling action of adjacent water-cooling pipe, the surface temperature of pipe 2−5 becomes bimodal distribution. The spatial arrangement has direct effect on the surface temperature distribution of water-cooling pipe. The local deformation of pipe 1 closest to the center of the RSC in water-cooling pipe without fixed is the largest, which is 5.20 cm. Maximum offset in π direction is 4.58 cm, far exceeding the pitch of water-cooling pipes, and the collision between water-cooling pipes is prone to occur. The overall deformation arises after water-cooling pipe is fixed. Maximum thermal deformation of water-cooling pipe with fixed is 3.28 cm, which is 36.9% lower than that of water-cooling pipe without fixed. The relative shift in the π direction basically disappears. Local deformation between the water-cooling pipe is smaller than the distance between the pipes. The occurrence of collision between water-cooling pipes is disappeared for the fixed action of the fixture. The changes of inlet syngas temperature and surface deposition affect the surface temperature gradient and deformation of water-cooling pipe with varying degrees, the offset direction is π/2 side of the water-cooling pipe.