Abstract:The practical blasting engineering is considered as rock mass engineering,and the general characteristics of rock mass blasting are discussed. There are various discontinuous joints and fissures in rock mass which have statistical characteristics,so the distribution parameter can be measured. The damage parameter is defined as the ratio of the area of fragmentation after blasting divided by the area of all sections. The definition meets the requirement that the damage of intact rock is 0 and is 1 after blasting. The rock fragmentation has fractal character and has relation between damage parameter and fractal dimension. So the evolvement equation can be established. The numerical calculation of the statistical damage model indicates that this model is clear in theory and applicable in practical engineering.