In order to study the important influence of flexible deformation of key component in vehicular missile weapon system on missile launching, the rigid-flexible coupling dynamics model of vehicular missile was built in virtual prototyping software ADAMS by using the rigid-flexible coupling system dynamics theory. The flexible body model of key component was set up by adopting finite element and Beam theory, and it was imported into ADAMS to complete assembly. Through the comparison and analysis of simulation results, the influence rules of two kinds of flexible body to missile initial attitude and deorbit parameters were achieved. The results indicated that the flexible body built by finite element(FEM) technique was more accurate and suitable for research needs.