Abstract: Many scientific problems, especially to understand and investigate the seismic precursor's complexity, has been proposed from the practice in observing and predicting Tangshan, Haicheng, Songpan, Lijiang strong earthquakes etc. According to the observed data of above earthquakes, we have a new conception concerning strong earthquake short-erm precursory complexity and its behavior. That is, short-erm precursory anomaly differs from trend anomaly, and the abruptness, divergence, special disorder, instability and unrepeatable property are their main characteristics. The relationship of “ield”and “ource”is also different from the normal “ield”and “ource”relationship; it has “haos”behavior. The origin of precursor anomaly complexity is not only resulted from the complicated system of seismogenic system, but the most importance is that the system is controlled by normal theory of non-inear geodynamics when it enters the inelastic strain deformation stage. So it seems to be impossible to study earthquakes and their precursory phenomena based on pure mechanics, they should be viewed as a part of non-inear dynamics system that acts as far away from equilibrium condition. Correlation analysis on seismic block, belt, source and precursor and progressive seismic prediction together with long-erm, middle-erm,short-erm and imminent judgment, is the summary of practice in successful and failure earthquake prediction. Only comprehensive analysis combining with time and space structures in a whole is able to grasp the basis of complexity of earthquakes and their precursors. We also discussed the earthquake prediction influence to the society, the social problems that prediction needs to face and the factors that confine or affect earthquake prediction and early warming. Comparing with other nature disasters, earthquake prediction and early warming are more difficult to do, and the decision in every step includes many uncertainties and risks whatever the warning issue, warning level adjustment or warming removal. The practice proves that government's synthetic decision to earthquake prediction, early warning and prevention are the key to effective reduce seismic hazard and risk.

Key words: Seismic precursor' complexities, Relationship of “ield”and “ource” “haos”behavior, Earthquake prediction, Early warning and prevention, Government' synthetic decisions