In this study,the structural morphology of the central segment of the LiaochengLankao fault and the relationship between its active characteristics and the tectonic stress field were explored.We first collected the focal mechanism data on 46 earthquakes ≤ft(2.0 ≤slant M L ≤slant 4.4\right) in the study area and performed seismic moment tensor overlay analysis to solve the overall focal mechanism. Results showed that the fault in the study area was a strike-slip fault with a thrust component. Then, we obtained the optimal stress field parameters in the study by using the grid search method and found that the strike angle and inclination angle of maximum compressive stress axis σ₁were 13.57^°and 12.89^°, respectively; the strike angle and inclination angle of medium compressive stress axis σ₂were 274^°and 36^°, respectively; the strike angle and inclination angle of minimum compressive stress axis σ₃were 120^°and 51.05^°, respectively; and the stress ratio R was 0.8. Second, the strike angle and dip angle of the fault were fitted by using the position of small earthquakes to investigate the fault morphology and were found to be 218.5^°and 84.43^°, respectively, and the rake of the fault was estimated to be 55.7^°on the basis of regional stress field parameters. Finally, on the basis of the combination of the stress characteristics of the study area and the stress distribution on the fault plane, we concluded that the middle segment of the Li aocheng-Lankao fault was mainly subjected to the tension in the NWW-SEE direction and the horizontal compression of the stress field in the nearly NNE-SSW direction. Under the action of this stress field, the fault moved in a mode of left-lateral strike-slip with a certain thrust component. This study provides more accurate information on the stress field in the study region. Such information is convenient for future research.