To implement GB/T 4732.3—2024 Pressure vessels design by analysis-Part 3：Formulae method，this paper systematically elaborates on the development practice and key considerations of the fixed tubesheet heat exchanger module in the SW7 software.The research focuses on several issues not mandated by the standard but of significant engineering significance，and conducts theoretical modeling，formula derivation，and functional expansion.The main contents include：Expanding the mechanical models to include the tubesheet embedded welding structure and the flat cover with a central nozzle opening，enhancing the engineering applicability of the software；Incorporating the effects of thermal bending deformation caused by temperature differences across the tubesheet thickness and the differential thermal expansion between the tubesheet and flange materials，achieving refined analysis of thermal loads；Based on the deformation coordination relationship of the flange-bolt-gasket system，proposing a method for determining a single bolt preload load that meets sealing requirements under multiple operating conditions；Innovatively proposing a nonlinear analysis theory for the variable‑stiffness elastic foundation plate，revealing the coupling mechanism by which tubesheet bending leads to a reduction in the axial stiffness of peripheral heat exchange tubes；Improving the stress evaluation system for key components such as the channel shell and shell‑side shell ends，and the flat cover，while clarifying the priority conditions for stability checks of heat exchange tubes and the criteria for selecting strength theories under biaxial stress states.SW7 software is not only a programmatic implementation of the new analysis and design standard，but also a beneficial supplement and engineering extension to the standard content.The release of its trial version is expected to promote the advancement of industry technical level.