Abstract: To implement the pre-stressed heat exchanger technology, numerical simulation of the thermal stress between the mutual restraint components and the deformation distribution under pre-deformation in the fixed tube sheet heat exchanger was performed. The new numerical simulation method named “Simulation in subsections, integration of the whole”, and CFD software to get the heat exchanger temperature distribution as a boundary condition for structural analysis in ANSYS. Pre-tension element to impose and control the amount of pre-deformation. The result of thermal-structure coupled analysis was obtained. The research methods were reasonable and feasible, because the simulation results agreed with experimental data very well. In addition, the experimental results and numerical analysis confirmed that by rationally imposing and controlling the amount of predeformation, the restraint between components (plates, shells, tube bundles) of fixed tubes heat exchanger in operation can be effectively alleviated and coordinated to create a good running environment and ultimately improve the operation reliability and service life of heat exchanger.