Through the observation and research of deep-well short-term and imminent electromag-netic information (E1) using whip-liked antenna,it is stated that: in time period 10 days to 4 months before an earthquake,three types of seismo-precursory signals such as short-immi-nent,short-term and imminent can be detected on l.9kHz and 2 7kHz underground signalchannel.The fact that the increasing and decreasing period of E1 is correspond to that of smallearthquake frequency in seismogenic zone stated that there may exist some relations betweenthe excitation of E1 and the mini fracture development in seismogenic zone, The dipolecharged body model (DCBM) proposed by us points out:the changing electromagnetic field iscomposed by three types of field such as qusi-static field,inductive field,and radiative field. Some quantitative results of these three type fields changing with observation distance and di-rection are given in this paper.