Seismic hazard evaluation is important for urban construction, earthquake disaster prevention and mitigation. However, because of the long recurrence times of large earthquakes (hundreds to thousands of years), seismic hazard assessment based on relatively short-term (tens of years) observational seismic catalog is difficult. Synthetic seismic catalogs provide a useful way to obtain long-term seismic hazard. Based on Coulomb failure criterion, we apply a quasi-static physics-based earthquake simulator (Virtual Quake) in a tectonically complicated region with several major faults, namely the Anninghe, Zemuhe, Daliangshan and Xiaojiang faults, in the Southwestern China. Slip rates of those major faults are constrained by the GPS data, and frictions are constrained by the laboratory experiments. Considering the stress interactions among the fault system, a synthetic catalog over 20, 000 years is simulated. The simulated catalog shows consistence with the observed seismicity in spatial distribution of large earthquakes, b value and mean seismic rate. The synthetic catalog also shows that the mean intervals of M≥7.0 earthquakes for the Anninghe, Zemuhe, Daliangshan and Xiaojiang faults are 299a, 867a, 361a and 90a, respectively. Our results provide a helpful index to evaluate seismic hazard in such a complicated region.