Abstract: Observation of parallel network electricity method indicates that apparent resistivity value goes up with the increase of rock failure degree.When the apparent resistivity value doubles,the fracture belt comes into being,and when the apparent resisitvity value is 3 times more than that of the background,the collapse belt forms.As the whole space detecting of resistivity is concerned,the measured values emphasize the difference between before and after the failure of upper covered strata.Results show that the conformation of the stratum structure failure and the evolution of rock stress can be observed dynamically with parallel network electricity method.This method is applied well and it provides a way to protect the safety of mining.