The numerical simulation of the cross-rolling stainless steel/carbon steel double metal composite seamless steel tube process was conducted through the finite element analysis of the three-dimensional thermo-mechanical coupled elastic-plastic by applying the MSC.MARC software. Based on the numerical simulation, The character of stress, strain and temperature distribution parameters during the two roll cross-rolling were obtained by the finite element analysis, and acquired the section pass deformation figure. The distribution of the axial stress, circle stress and radial stress were drawn in the cross-rolling roll gap profile along the circle. The mechanism of tube cross-rolling process was explained according to the stress distribution. The results of the research can be applied to the design of the cross-rolling forming process.