Abstract: This paper studied the space-time evolution characteristics of East China with the method of improper slave function in fuzzy mathematics, which studied 50000 sets of com prehensive precursor field data observed by six teen methods of precursory observation. Through the study, we can conclude that improper slave function shows fairly good earthquake-reflecting capacity to earthquakes with M_s 5. 0 in eastern China, Which can be regarded as comprehensive parameter to the medium-term and short-term earthquake prediction and can determine three elements of an earthquake mo re exactly.

Key words: Precursor field, Slave function, Eastern China region