The fitting method is used for obtaining the constitutive relation of ultra-high strength steel in this pa-per. At the same time,the forming limit of material is researched under different deformation conditions. Through experiments,the paper obtains stress-strain curve under different deformation temperatures and strain rates. On the basis of experimental data,the constitutive relation model is established which can reflect the de-formation capacity of ultra-high strength steel during process of hot stamping. Combining with finite element simulation results of hot stamping by the commercial software AUTOFORM,transfer path of load and match-ing law of strength,the paper determines the design criteria and forming process requirements of parts manufac-tured by hot stamping. Through setting different process parameters,such as punch velocity and friction coeffi-cient,and blank shape,the paper finds that process parameters and blank shape have an essential effect on the quality of parts.