A relation between the Young’s modulus and the martensitic transformation during TRIP sheet steel stamping is investigated. A TRIP steel, TRIP600, is used to study the phenomenon. The transformation kinetics under different loading paths were gotten through simple-shear, uniaxial tension, plane strain and equibiaxial stretching tests. The Young’s modulus, which plays an important role in accurate springback prediction for TRIP steel sheet stamping, is changed with the martensitic transformation during TRIP steel deformation. To improve the accuracy of springback simulation, the constitutive model of the TRIP steel is developed considering the variation of the Young’s modulus with the martensitic transformation. The accuracy of the proposed method is verified by the experimental results.