Computer simulation can be utilized to predict the property and quality of heat-treated products. The prediction accuracy depends upon the thermal boundary condition and the thermal history from which surface heat transfer coefficient (HTC) is derived. Variables studied are thermal boundary and the surface HTC. Zone-based thermal boundary is set with and without edge effect. Lumped heat capacity method is used to predict HTC of silver probe (1st step), then iterative modification method is applied to the prediction of HTC of SUS304 cylinder (2nd step) and S45C cylinder itself (3rd step). Using FEM tool of DEFORM-HT combined with lumped heat program LUMPPROB, this research is intended to obtain the number of thermal boundary and iterative modification step. The higher accuracy is obtained by employing the edge effect of thermal boundary. The 2nd step significantly increases the prediction accuracy of radial distortion and residual stress distribution. However, 3rd step does not significantly increase the prediction accuracy.