Abstract At first, the environment of seismic precursor occurrence, the relations betwen subsurface fluid action or subsurface fluid force and seismic precursor are analysed. Besides the occurrence process of seismic precursor anormalies in shallow crust and deep crust is expanded and exampled. Lastly,a view of seismic precursor from ‘double force source’ is further discussed, the main points are as follows: seismic precursor is the result from the action of ‘double force source’, namely tectonic stress and the subsurface fluid force which each other growth and decline produce different dynamic figure and seismic precursor anomalies;the tectonic stress is primary and the subsurface fluid force is modulating on the process of earthquake development and seismic precursor occurrence that may be occured only when the subsurface fluid force mechanicaly couplling with the tectonic stress of earthquake preparation on its enhancement process may modulate and induce earthquake precursor and promote earthquake occurrence.
