Abstract: This paper stated Professor Luo Lange's research idea about the information magnitude of earth quake precursors.On the basis of analysing some basic characteristics possessed by the information magnitude of eatthquake precursors in a systematic way,he made these characteristics to be highly summarized and abstracted,and gave out the synthetic mathematics expression of information magnitude of earthquake precursors.Through calculating for the real earthquake observational data,it showed that not only can this expression unitedly transfer the lasting anomalous variations of various earthquake observational data into the information magnitude of earthquake precursors,but it can also describe precursory information continuity possessed by the anomalies which are termination in a quantitative way.Thus,the precursory informations shown by earthquake anomalies are made much more clear,audio-visual and complete.This has established the foundations for us to further more explore evolutionary regularity in time and space of colony precrusory in formations of earthquake anomalies and effectively develop the study of earthquake synthetic prediction.