The shape of seismic fault zones is essential for the study of active tectonics and geodynamics. The Maduo earthquake sequence that occurred in 2021 provides rich focal mechanism data and a suitable opportunity for counting the nodal planes of focal mechanisms and estimating the geometry of the seismogenic fault. Herein, the seismogenic fault geometry was determined using a density-based clustering algorithm to analyze the focal mechanism data. First, the central focal mechanism of the Maduo earthquake sequence was solved to obtain accurate data. Then, the results of a strike of 113.5° and a dip of 88.2° were obtained using the DBSCAN method. Finally, by inversion and projection of the stress field on the fault, the relative shear stress and relative normal stress were obtained as 0.84 and -0.79, respectively, and the sliding angle was estimated as -0.72°. The results show that the Maduo earthquake was caused by the stress of northeast-southwest compression and northwest-southeast extension. Then, a large shear stress was generated on the Jiangcuo fault with a nearly east-west orientation, thus causing a left-lateral strike-slip dislocation on the fault.