Abstract: This paper uses seismic data from Yunnan Regional Digital Seismic Monitoring Network and Tengchong Volcano Seismic Network, and adopts the double-difference location method to relocate the 2011 Tengchong M_S5.2 double-earthquake sequence. After double-difference relocation, the spatial distribution of epicenters converges significantly, and the focal depths are concentrated at 4-6 km. Driven by the coupling of the Longchuan River fault, the Longchuan River water system, and deep hydrothermal fluids, the epicenters of the earthquake sequence migrate reciprocally along the SE-NW direction. Combined with the spatio-temporal migration characteristics of the earthquake sequence and the fault plane solution, it is inferred that the seismogenic fault of this earthquake is a hidden fault with a NW137° strike. The fluid diffusion coefficient is 0.3703~1.5046 m²/s, which supports the "rupture-fluid diffusion-pressure accumulation-re-rupture" mechanism. The analysis of focal mechanism consistency shows that the S-P time differences between the foreshock sequence and the first main shock sequence are concentrated at 4.6-5.1 s, and the P-wave first motion consistency parameters K are 0.9824 and 0.9436 respectively. The discreteness of the second main shock sequence is significantly enhanced (K=0.7272). The research results have important reference value for earthquake prediction and earthquake prevention and disaster mitigation in the western Yunnan region.