In order to study the mining crack evolution process of the overlying strata in goaf, based on the numerical method for meso rupture mechanics characteristics of coal rock, combined with nonlinear fractal geometry theory, the evolution process of mining crack and quantitative description of the spatial and temporal characteristics were researched. The results show that the overlying strata deteriorated continuously under mining, simultaneously, the internal meso damage accumulation of rock eventually cause the overlying strata failure. The acoustic emission in the cracks evolution process is with self-similarity. The fractal dimension increases firstly with a small amplitude after loading, and then sharp declines, especially decreases to a minimum value before damage. It is considered to be a effective indicator in evaluation of overburden damage. By means of the overlying results, the overburden fractured evolutionary mechanisms are explained perfectly, and it is able to guide forecasting and control practice of rock stability before disasters.