Base on CSP process, the grain refinement mechanisms of Re on X65 pipeline steel was analyzed by the hot simulation experiment of X65Re and X65 pipeline steel. Experimental results show that rare earth Ce can inhibit recrystallization behavior of X65 pipeline steel, strain energy can be accumulated during hot deformation process. After multi-pass processing, the accumulated deformation energy can provide a driving force for ferritic phase transformation, therefore the microstructure grains can be refined.