A notable earthquake swarm occurred near the Shuangbai and Eshan area and its activities continue since 09:58,May 19,2015.The largest magnitude is M_L4.1 which occurred on June 14. We relocated this swarm by using hypoDD method. It has been shown that:the earthquake swarm distributed along the Lvzhijiang fault,and the dominant direction of relocated aftershocks is more obvious than before. The focal depths are at 6~12km,and 8~10km underground is the dominate layer where earthquakes can occur more easily. In comparison with original data,the RMS average value of arrival residual decreases form 0.303s to 0.034s,and the average error is 0.21km in EW direction,0.13km in NS direction and 0.175km in vertical direction. We calculated the focal mechanisms for earthquakes with magnitudes larger than M_L2.5 by using an inversion technique for focal mechanisms of local and regional earthquake,named Generalized Polarity and Amplitude Technique(GPAT),and 24 results were obtained in the end. The results show that the main type of focal mechanisms for this swarm is normal,and this is not the same as before. On the basis of the water level of the Longmen reservoir dam and the frequency and magnitude of the earthquakes,we suggest that the activities of this swarm are closely related with the process of reservoir inpounding. This swarm is the result of a normal fault movement which was caused by the reservoir inpounding.