In this work, the hot rolling process of SiCp/2009Al composites is simulated using the fully coupled thermal-stress analysis in Abaqus/Explicit. By the investigation of formation process for rolling along with different fields of temperature, strain rate, strain and stress and their evolutionary history, the hot rolling mechanisms under complicated stress states is achieved. The results show that the maximum principal stress changes from compressive stress to tensile stress at the stage of rolling entrance and a reverse trend replaces it at the exit, and that the compressive stress is dominant in the deformation zone at the steady rolling stage. The temperature drop effect due to heat transfer is far greater than the temperature rise effect due to friction on the plate surface while the temperature rise is embodied in the center due to plastic deformation. Besides, the effect of strain rate on flow stress plays a leading role at the entrance and exit stage, and the flow stress on the plate surface in the deformation region is mainly determined by strain and temperature except the stick zone which is controlled by strain rate, however, the center flow stress in deformation is mainly affected by temperature.