In this paper, we employ the extended finite element method （XFEM） to assess the impact of new crack within fault stepover on the earthquake rupture propagation scenario. The initiation of new cracks in the model follows the maximum shear stress failure criterion. When the maximum shear stress surpasses the strength of rock, the intact medium undergoes fracturing, resulting in the formation of new crack. The extension direction of these new cracks aligns with the directions of maximum shear stress. Through XFEM simulation, we observe that the new crack within the fault stepover alters the fault’s geometry and the stress distribution after fault ruptures. The presence of a new crack can modify the spatial distribution pattern of Coulomb stress, particularly by increasing the stress level along the fault. Consequently, the ability of earthquake rupture propagation across a stepover is enhanced. Our simulation results demonstrate that the earthquake rupture can spread across 10-km-wide fault stepover due to the occurrence of new rupture within the stepover, and if there is no new crack in the inner part of the stepover, ruptures cannot traverse the fault stepover. Therefore, this research contributes to a deeper understanding of the earthquake spontaneous rupture propagation process across fault stepovers. The findings hold significant scientific importance for analyzing earthquake rupture propagation process and assessing earthquake disasters.