An earthquake results from release of strain energy of an active fault under the action of regional tectonic stress field.The seismic failures of surface buildings and structures as the results of the action of tectonic stress field certainly have the same mechanical properties as the seismic deformation belt.In the present paper.the author fully proves the existence of predominant directions of seismic ground motion by analyzing the earthquake disasters of some strong shocks and points out its importance in earthquake resistance and disaster prevention.engineering designs against earthquake and earthquake damage prediction.