There were three strong earthquakes to occur from July 12, 1995 to February 3, 1996 in the Yunnan province and its vicinity. These earthquakes formed a phenomenon of successive occurrence of multiple events. In this case, it is necessary that the precursor fields are formed by every earthquake to superpose mutually. The mixture precursor fields may be separated by the hierarchy method. And principle of separating mixture precursor fields is discussed. The results are following :(1)When precursors of different hierarchy of every earthquake meet each other, its synthetic amplitude becomes very big due to superposition. (2)When the appearing times of precursor of different hierarchy of every earthquake are near, the group of jump-like precursor appeared. (3)If an strong earthquake not only has obvious precursor, but also has obvious precursor-like after the earthquake, there will be other strong earthquakes to occur in the near future time. (4)If in the later period of the multiple source system, the anomalies muchmore become weak, it means that procedure of generating earthquake of the multiple source system is going to end