The Yangbi MS 6. 4 earthquake occurred at 21:48 on May 21, 2021, in Yangbi County, Dali Bai Autonomous Prefecture, Yunnan Province. The Yangbi MS 6. 4 earthquake sequence from May 18 to Aug. 22, 2021, was relocated by the double- difference algorithm. The relocation results show that the earthquake sequence is distributed in the NW direction. The length and width of the rupture are approximately 20 km and 7 km, respectively. Location error estimates show that the lengths of the 95% confidence ellipsoids axes are less than 2. 0 km. The estimated location uncertainty is approximately 0. 8 km in horizontal and 1. 0 km in vertical directions. The Yangbi MS 6. 4 sequence is a linear concentration in NW direction in the northwest segment. It is divided into two branches in NW (main faults) and NNW (branch faults) in the central and southern regions. The main fault has obvious segmentation, and the branch faults are distributed in the echelon. It is known that clustered small earthquakes often occur in fault plane vicinities of large earthquakes. Precisely relocated earthquakes estimate fault plane parameters of the main faults. The results show that the strike and dip of the main fault are 320° and 89° at depths of 3~13 km. The main faults and branch faults projection on the surface is on the west side of the Weixi- Qiaohou fault and near the Caoping fault. The Caoping fault, a secondary fault on the western boundary of the Sichuan- Yunnan block, may be the seismogenic fault of the Yangbi MS 6. 4 earthquake. The linear characteristics of the Caoping fault are not significant in the remote sensing image, and its late Quaternary activity is weak. It suggests that the secondary faults with weak activity on the boundary of the blocks should be paid more attention to the further seismic risk analysis. Three asperities were distinguished on the fault plane based on the slip distribution of the rupture fault plane. The initial ruptures occurred in asperity in the mid- segment of the fault. They triggered the main shock in asperity in the northwest segment of the fault. Within one hour after the main shock, the rupture propagated from northwest to southeast along the strike of the fault plane, which shows a significant directionality. The rupture process reveals that the initial ruptures in one asperity would trigger the main shock in the neighboring asperity. Finally, all adjacent asperities would be fractured. It is an efficient way to predict earthquakes by identifying the asperities on the fault plane more accurately and effectively in the future.