Abstract: In this paper,based on the method of calculating earthquake anomalous precursory information magnitude given by document1,the anomalous variations of presentation of various precursory observation means in Hebei province and its vicinity before 1989 Datong Ms 5.8 earthquake were analysed in a systematic way and precursory information magnitude provided by these anomalies was calculated.On the basis of this,the dynamic images of precursory information field in time and space before Datong earthquake were got up and its evolution active characteristics were studied.