Pre-produced triplate transition joint assemblies are widely used in shipbuilding industry to make welds between aluminum and steel for a number of years now. The straight-shaped transition joint assemblies are bent during shipbuilding. So it is necessary to study the residual stresses created by punch forming, which would have heavy effects on the quality of structural parts. ABAQUS is a suite of powerful engineering simulation programs, based on the finite element method. In this paper, ABAQUS was used as the main tool to simulate the residual stresses in a triplate transition joint after unloading. Punch-pressing was carried to simulate bending moment in ABAQUS. The triplate is consisted of baselayer (steel: Lloyd’s Shipplate Gr. A), interlayer (pure aluminum: Al99.5) and superlayer (Al-Mg alloy: AlMg4.5Mn). Results from the ABAQUS analysis showed that increasing the radius of punch significantly reduced the von Mises residual stresses in steel. Changes of von Mises residual stresses in interlayer (Al99.5) and superlayer (AlMg4.5Mn) were negligible.