Abstract：Based on focal mechanism solutions of the Yangbi earthquake sequence and historical earthquakes, we preliminarily analyze types of the focal mechanism solutions and distribution characteristics of stress axis. Further, we analyze the relationship between the focal consistency parameter and the Yangbi earthquake and historical moderate and strong earthquakes. The results show that the types of focal mechanism solutions of the Yangbi earthquake sequence and historical earthquakes are mainly strike-slip earthquakes, followed by normal earthquakes. The average Misfit angle in different radii have a certain corresponding relationship with the moderate-strong earthquakes such as Yangbi MS6.4. The focal mechanism consistency parameter all decreased before these earthquakes; that is, the focal mechanism solutions tended to be consistent. At the same time, according to the calculated b-value changes, moderate and strong earthquakes in the study area also mostly occurred in the period of b-value decline or low b-value period. When the source consistency parameter Misfit angle in the study area is lower than 40° and begins to decrease, it may indicate that the regional tectonic stress starts to concentrate. The earthquake is gradually approaching, and the risk of strong earthquakes is increasing.
