Abstract: This article collected broadband seismic waveform and phase data recorded by the Qinghai and Gansu regional seismic networks. The focal mechanism solution and centroid depth of the Subei M_S5.5 earthquake in Gansu on October 24th, 2023 were obtained by performing centroid moment tensor inversion with ISOLA software. The precise hypocenter results and spatio-temporal distribution characteristics of the earthquake sequence were obtained through the double-difference relocation method, and an analysis of the seismogenic structures was conducted based on the structural background of the area. The focal mechanism solution parameters of the Subei M_S5.5 earthquake are as follows: the strike, dip and slip angles of nodal plane I are 170°, 73°and 108°, respectively. The strike, dip and slip angles of nodal plane II are 300°, 24° and 42°, respectively. The main shock centroid depth is 4 km. After relocation, the epicenter of the earthquake sequence was concentrated in a region about 22 km long and 10 km wide, and the dominant direction of the earthquake cluster was NNW-SSE. Based on the analysis of focal mechanism solution, relocation results and regional tectonic background, we infer that the focal mechanism solution plane I is the seismogenic fault plane, and the earthquake is a predominantly thrust faulting with strike-slip event occurring on the hidden fault, and the seismogenic fault has the same property as the surrounding major faults.