Abstract：The new calculation method of structural surfaces with different scales is given on the basis of block discrete element method(DEM) in which contacts face to face. Moreover，a new discrete element model for simulating rock and soil blasting problem is built. The elements of new model can be split by itself in the program. There are small scale blocks around the charge，and large scale blocks are adopted in far zone. And the new calculation method between different scale structural surfaces is added in the model. So it can depict the scale effect of structural surface in rock mass more accuracy. In addition，some stimulated examples of rock blasting are showed by the new calculation method. The following two rules can be gotten from these examples. (1) The destruction characteristic of rock mass near the charge is obtained by simulating the stress and strain fields. Comparing it with the results obtained from the primary block discrete element method，it can represent the effects of the breakage of rock mass around charge on stress fields in near area. (2) For some rock and soil phenomena，such as blasting crater and drum，the simulated results by the new model can fit well with the experimental formula.
