The line heating process has long been used in plate forming of hull surfaces and it has depended on skillful workers. Since reduction of production cost is a major concern of shipbuilding companies, line heating work must be improved for higher productivity. In this paper, as a first step to automatic hull forming, a method is proposed to predict deformations due to line heating. It includes a simplified thermal elasto-plastic analysis to increase computing efficiency and to enable real-time visualization of deformed shapes. The simplified thermal elasto-plastic analysis method shortens the thermal elasto-plastic process and introduces inherent strains. Predicted deformations for line heated plates show good agreement with experimental results. For the prediction of deformation, a method to estimate heat flux of the torch is also introduced. The proposed method can be used in control and simulation of the line heating process with simplicity and efficiency.