Abstract: The concept of thermal differential mouldless forging and the method of generating large thermal differential are introduced first.The process of local heating and local cooling on cylinder billet is analyzed by the ANSYS software.In the thermal analysis,the initial temperature of billet、beat fluxes(heat flow per unit area)of positive and negative value and convections to surrounding air are considered.By orthogonal experiment,the main correlative parameter for obtaining the optimal temperature distribution is acquired,which is preparted for the analysis of the stress-strain field in the process of performing thermal differential mouldess forging.