Abstract: This paper selected the Euclidean distance D_FM to measure the focal mechanism consistency between different earthquakes, and analyzed the relationship between the consistency of focal mechanism and D_FM value taking the 1975 M_L7.3 Haicheng earthquake sequence and 1999 M_S5.4 Xiuyan earthquake sequence as examples. The result shows that when D_FM is below 50 the two focal mechanisms become extremely consistent. In order to determine consistency of a number of focal mechanisms the significance test method is drawn into. According to the consistency parameter K proposed by Chen Y, we investigated the consistency of focal mechanism for small earthquakes prior to the M_S5.4 Xiuyan earthquake using sign test and Z test. The result suggests that the focal mechanisms of small earthquakes occurred near the M_S5.4 Xiuyan main shock are significantly consistent with each other with confidence of 98%. Therefore the method proposed in this paper can be applied to practical earthquake prediction effectively.