The crack propagation of negative moment zone of steel-concrete composite beams with initial concrete cracks was numerically simulated, using the extended finite element method (XFEM), based on the finite element software ABAQUS. The correctness of the numerical simulation method was verified by comparing it with the existing model tests. It is found that the crack propagation and mechanical properties of negative moment zone of steel-concrete composite beams with initial concrete cracks are affected not only by the size and location of single cracks but also by the relationship between the locations of multiple cracks; among them, the location of transverse distribution of cracks and the location of longitudinal distribution of cracks are the main factors affecting the crack propagation of negative moment zone of steel-concrete composite beams with initial concrete cracks.