In shipyard, triangle heating technology with irregular multi-heating paths and highly concentrated heat input is used to form a curved plate, especially a concave type plate. Compared with line heating process with simple line segment path, its main purpose is to get a bigger contraction deformation at the plate edge. Hence, triangle heating technology is important for most shipyards to increase hull-forming productivity and study the automation. This paper focuses on the moveable triangle induction heating technology. An electromagnetic coupling finite element model is built to simulate the moveable triangle induction heating process and reveal the temperature characteristics and deformation behavior. The results of the simulation are compared with those obtained from experiments and show good agreement. It demonstrates that the numerical model used in this study is effective for simulating triangle heating for the steel plate forming process in shipbuilding. With the numerical model, the paper further investigates the effect of heating parameters on temperature and shrinkage deformation. These are traced here with a modified mechanical model whose results are in accord with the numerical results. This modified model can be applied to predict the edge shrinkage and explain the effect of heating parameters on transverse shrinkage.