Complicated changns occur inside the steel parts during quenching process. The abruptly changed boundary conditions make the temperature field,micro - structure and stress field change dramatically in very short time, and these variables take a contact interactions in the whole process. In this paper, a three dimensional non - linear mathematical model for queeching process has been founded and the numerical simulation on temperature field,microstructre and stress field has been realized.In the FEM analysis, the incremental iteration method is used to deal with such complicated nonlinear as boundary nonlinear, physical property nonlinear,transformation nonlinear etc.The effect of stress on transformation kinetics has been considered in the calculation of microstructure. In the stress field anal- ysis,a thermo- elasto - plastic model has been founded, which considers such factors as transforma- tion strain,transformation plastic strain, themal strain and the effect of temperature and transforma- tion on mechanical propertier etc. The transient temperature field, microstructure distribution and stress field of the roller on any time can be displayed vividly,and the cooling curve and the changes of stress on any position can also be given. The abruptly changed boundary conditions make the temperature field, micro-structure and stress field change dramatically in very short time, and these variables take a contact interactions in the whole process. In this paper, a three dimensional non - linear mathematical model for queeching process has been founded and the numerical simulation on temperature field, microstructre and stress field has been realized. the FEM analysis, the incremental iteration method is used to deal with such complicated nonlinear as boundary nonlinear , physical property nonlinear, transformation nonlinear etc. The effect of stress on transformation kinetics has been considered in the calculation of microstructure. In the stress field anal- ysis, a thermo- elasto - plastic model has been founded, which determines such factors as transforma - tion strain, transformation plastic strain, themal strain and the effect of tempe rature and transforma- tion on mechanical propertier etc. The transient temperature field, microstructure distribution and stress field of the roller on any time can be displayed vividly, and the cooling curve and the changes of stress on any position can also be given.