The crystal plasticity finite element method (CPFEM) has been adopted to simulate the nanoindentation of single crystal high manganese twinning induced plasticity (TWIP) steel in Abaqus environment through the user-defined material subroutine (UMAT). The nano-indentation experiments were performed on the annealed TWIP steel with Berkovich tip with two levels of load and the initial crystallographic orientation of the testing material was examined by means of electron backscattered diffraction (EBSD). By adjusting the input parameters in UMAT, the CPFEM model can be verified by matching the numerical and experimental load-displacement curves, and by comparing the calculated young's modulus between simulated and real one. Three unknown self hardening parameters were affirmed by this fitting method. The surface profile, pole figure, and lattice rotation angles derived from the optimal CPFEM model. There is a mutual proof between TEM observations of deformation twinning and simulated lattice rotation angles.