Abstract: Dynamic evolution law and fissure forms of overlying strata compaction area were studied by using similar materials physical similarity simulation and theory analysis.The research results show that the separation values are distributed with the shape of “saddle”and there is a stress concentration in a certain area in gob floor and the bottom boundary of compaction area can be determined by combining both theories. Fissure forms and the dynamic evolution law of goaf overburden rock compaction area are affected by both mining height and advanced distance, which provides the relationship between the evolution law of the width, high of compaction area, caving angel and mining height.Meanwhile, the mining height effect of the compaction degree in compaction area has been analyzed by combining the bulking factor characteristic of caved rock area and the feature of stress concen-tration in bottom. In a certain range, the higher of the mining height is, the larger compaction degree will be.Based on the theory of elliptic paraboloid zone and the analysis of experiment results, the mathematical expression equation of mining fracture compaction area is established which provides a theoretical basis for the distribution and parameter optimization of pressure relief gas extraction system.