Abstract: A constitutive model of Carbon Fiber Reinforced polymers (CFRP)composites was established based on the experiment and simulation analysis. Analyzing the static stiffness and dynamic mechanics of the body in white (BIW) cab of a commercial vehicle, and selecting the CFRP composite material as the material of the cab model, a steel/CFRP hybrid material structure was designed and solved by finite element software Nastran. The simulation results show that the rigidity of the cab model after weight reduction can remain basically the same with that of original cab, but its first-order torsional frequency is increased by 27.3%, and the overall quality of the BIW cab is reduced by 37.9 kg, a reduction of 11.3%. The obvious lightweight effect can prove the CFRP composite materials broad prospects in the automotive lightweight field.