Abstract: On the basis of analyzing the influence of explosion in rock breaking and the relationship between the occurrence of structural plane of rock mass and explosive package, we summarized the rock breaking mechanism of chamber blasting in the case of open chamber blasting by analyzing the four cases just as faults passing the position of charge, faults intersecting with the line of least resistance, faults intersecting with the blasting crater and faults outside the blasting crater. When faults are encountered in the process of drilling and blasting in open pit mines, it should consider different position relations to reasonably use of "avoiding", "controlling", "blasting" method to minimize the adverse effect of fault.