Abstract: The observation data of each precursory approach from 1970 to June 2000 in Hebei Province are processed.Based on the method of synthetic probability,the index of synthetic probability to determine medium and strong earthquakes with multidisciplinary precursor is picked up (P≥0.55).The results are corresponding well with the M_s≥5.0 earthquakes in Hebei province ad its adjacent area.The R-value for the method is 0.467.It indicates that the method has some prediction ability in some extent.