The result of presplit blasting influenced by geometrical characteristics of joints are combining studied by the software AUTODYN 2D and UDEC. By calculating

the impact of geometrical characteristics of joints can be found through the crack extension between the blasting hole. The straight level of the cracks between the blasting hole are gradually enhanced with the increasing of angle between the joints and the borehole connection; and the angle of 90-degree can get the best result that the crack will be coincided with the borehole connection; and it is also in accord with the theoretical analysis. Joints space has significant impact on the presplit blasting; and the smaller joint space the rock has the more difficult the cracks connected. Reducing the space of boreholes is conducive to form the linked up cracks.