The development and evolution of strike- slip fault zone is closely related to the formation and evolution of pull- apart basin. The secondary faults and pull- apart basins developed under different overlapping ranges of the main faults have different scales and shapes. Previous studies have mostly used physical simulation to study the evolution process and fault development characteristics of strike slip pull- apart basins. There is a lack of analysis of fault deformation characteristics during the evolution of basins and the discussion on the law of fault evolution under different degrees of overlap of main faults. Based on the discrete element simulation software PFC2D, this paper simulates the development and plane evolution law of faults in the pull- apart basin under three conditions: underlapping, neutral and overlaping. The results show that the fault development of the pull- apart basin experienced a process that faults development from the ends of the strike- slip main faults to the internal releasing bend and then expend to the exterior ,and regardless of the degree of superposition of strike- slip main faults, the law is well reflected. In addition, the high degree of overlap between the fault development position and the stretching area indicates that the development law of the fault is of great significance to the migration of the depocenter of the pull- apart basin.