Reliable source slip-distribution models of moderate and large earthquakes are important not only for understanding earthquake source physics but also for making realistic seismic hazard assessments. In this study, we carry out the inversion for finite-fault rupture process of the 2014 Ms 6.5 Ludian earthquake in a structural model with 3D velocity heterogeneity and surface topography. To ensure efficiency in calculating 3D synthetics during slip-distribution inversions, a database of strain Green’s tensors (SGTs) is established for the structural model. We then use the SGT database approach to perform the source slip-distribution inversion for the Ludian earthquake using regional broadband seismic records. The accommodation of lateral velocity heterogeneity and surface topography reduces modeling errors in source inversion. The finite-fault slip model indicates that the Ludian earthquake rupture initiated from the hypocenter and propagated southeastward and upward, reaching the ground surface with a surface rupture of ∼16 km in length and a maximum left-lateral slip of ∼1:2 m, in agreement with the findings of field surveys after the earthquake.