Creating an access opening in ship structure through thermal cutting is an important process in ship repair and reconstruction. The flame cutting process typically leads to a nonuniform temperature distribution, generates residual thermal stress and localized plastic deformation. As openings are needed at various locations of ship hulls, it is also necessary to consider the effects of structural constraints in the immediate end of the plate where the plate is either welded or fixed to the ship frame or bulkhead. These are challenging tasks. This article presents a study based on the thermal elastoplastic analysis. By using the finite element techniques, a steel plate model undergoing flame cutting process to create an opening was studied in details. The numerical model was validated with experimental data. The study identified several key parameters that are 1) structural boundary condition, 2) steel plate size, 3) opening location, and 4) opening shape.