Abstract: Over 12 years ground tilt data observed in the 9 seismostation in Hebei province and its adjacent area are processed with the methods of harmonic analysis and periodical filtering.We first extract anomalies with the uniform standard,then calculate the probability's increasing for each seismostation corresponding to earthquakes,at the end we make one station synthesis and mulit station synthesis.The results show that when the probability synthesis curve exceeds 0.05,an Ms≥4.8 earthquake will occur in half a year.