In order to test the practicability of spectral clustering for focal mechanism solutions,we took Xinfengjiang reservoir as the case study area and applied a mechanism inversion to seismic events(M_L≥2.0,2012-2018),by using P wave polarity and amplitude ratio of P and S wave. Then,spectral cluster analysis was applied to these focal mechanism solutions which were clustered 7 types finally. By analyzing the temporal and spatial characteristics of each cluster,we investigated the relationship between clusters and regional structures and reached following conclusions:① The earthquake rupture type in Xinfengjiang reservoir is majorly normal-faulting type with partial dip-slip components,and is slightly strike-slip type. ② Mechanism variations were strongly associated with corresponding hypocentral structure,which reflected the relationship between seismic activity and structures in Xinfengjiang reservoir. ③ The faults described by clusters reflected the structural conditions of reservoir water infiltration,that explained the possibility of frequent regional earthquakes,in Canyon and dam area. ④The clusters changed relatively steadily within the research time frame.