Inversion for focal parameters is a method of analysing the focal body. In the instant of an earthquake occurring

a coseismic deformation step can be recorded by automatic deformation observation equipment with high sensitivity

by which the earthquake fault parameters can be inverted applying certain fault dislocation model. Before an earthquake

the degree of order of crustal deformation increases apparently with temporal and spatial anomalies of deformation field. According to the correlation between the anomalies and the coseismic deformation step

the focal parameters can be inverted by precusor field data of deformation before the earthquake

on which the research of earthquake prediction can be carried out. In order to predict earthquake by this means

the following problems are required to be solved: 1.the analysis and study of mechanical state of precusor field; 2. the study of nomalization of precusory observation data for inversion; 3. the selection and check of focal parameters model for inversion: 4. applying inverted focal parameters in earthquake prediction. To solve these four problems

by analyzing stress states in the process of an earthquake according to the theory of static dislocation source

the fault parameters of the earthquake are inverted by using high resolution strain data recorded by sensitive instruments during earthquake. Earthquake examples are calculated after geodetic deformation data and physical precusor data are scaled and normalized respectively. In order to understand the stress process in rock adjacent to earthquake hypocenter and its effects on deformation instruments installed in rock

a chemical fracturing test was carried out in a large tunnel of Xuzhou synthetic deformation station

where various types of defomation instruments with high sensitivity were installed

to simulate the stress state in different structure and distance in the vicinity of fracturing point. The decay law of strain was observed

which gave the relationship between released energy and distance in different tectonic direction. The software for hypocenter parameters inversion and precusor field data normalization were worked out. By inversion of deformation data during earthquake for seismic fault parameters

a new kind of earthquake prediction means is proposed and some progresses have been achieved.