We solved the five focal mechanisms of moderate and small swarm earthquakes occurring since 1999 in Yingkou and Haicheng using the P-wave first-motion method. We defined the sum of the inclinations of three orthogonal and principal stress axes of the focal mechanisms for the moderate and small earthquakes and that of the tectonic stress field in corresponding areas in the 3D coordinate system as parameter of the consistency of the mechanisms. It is a quantitative index used to measure the release stress field of an earthquake source and the conformance degree of the regional tectonic stress field. The conformance degree of the regional stress field and the focal mechanisms increase as the value decreases. The conformance degree of the regional stress field and the focal mechanisms of moderate and small earthquakes are higher because of the enhanced tendency of the regional tectonic stress field and higher possibility of occurrence of a stronger earthquake in the future. The result shows that the parameter of the consistency of the focal mechanisms was reduced to a minimum value of approximately 10~60 days before the occurrence of larger earthquakes for the earthquake swarms in Yingkou and Haicheng. Time and fluctuation range of the low value may be related to the characteristics of the earthquake swarm. The consistency parameter fluctuated significantly in common swarms such as the 2008 Haicheng earthquake swarm and the 2012 and 2013 Qingshiling earthquake swarms in Gaizhou City. All the mean values of the consistency parameter were greater than 125°. The value was low before the occurrence of the two stronger earthquakes (M5.4 on November 29, 1999 and M5.1 on January 12, 2000) in the foreshock sequence in Xiuyan. The value varied between 20° and 30°, and the minimum value was less than 65°. The consistency parameter did not vary significantly, and the mean value is not high (73°) for the 2014 earthquake swarms of Xihaiyu and Gaizhou, thus indicating some strengthening tendency of the stress field. However, because the consistency parameter is not consistently low, further research must be conducted in the future. Nevertheless, the parameter of consistency of focal mechanism is more useful for judging the stress condition in the focal region than using the P-axis trend of focal mechanism.