Abstract:Based on the waveform records of 9 seismic stations belong to Hubei and Jiangxi regional seismic network, we obtained the focal mechanisms of the Ms 4.6 JiangxiRuichang earthquake on September 10 in 2011 with the CAP method. The result shows that the best double couple solutions are 204°, 79°and -22° for strike,dip and slip angles, respectively, the other nodal plane is 298°, 68°and -168°. The optimum focus depth is 14 km. The result shows that the principal stress P axis of the earthquake is mainly in NS, the lord tension T shaft is mainly in EW; the biggest aftershock is Ms2.8 which is also normal dipslip fault. And aftershocks sequences mainly propagated along NEE, very few aftershocks propagated along NW. So we infer that the Ms 4.6 earthquake and aftershocks are caused by the NE strike in Fenlinqiao fault from the earth’s surface investigation, and the seismogenic structure is the same to the Ms 5.7 Ruichang earthquake in 2005