The invention relates to engineering geology three-dimensional modeling analysis and discloses a GOCAD-based dam foundation rock mass blasting relaxation analysis method. The method solves the problems that a dam foundation rock mass blasting relaxation analysis scheme in the prior art is difficult to fully express the spatial distribution rule of rock mass blasting relaxation, the statistical drawing workload is large, and spatial region statistics cannot be carried out. The method comprises the following steps: obtaining a parameter Vp value which is obtained before and after blasting and can represent rock mass blasting relaxation; the parameters are used for speculating the spatial characteristics of the blasting relaxation rock mass through a DSI algorithm, so that a blasting relaxation rock mass model is constructed in GOCAD, blasting relaxation index attributes are created on the model, and the C language is used for operating the parameters to obtain indexes for visually reflecting the blasting relaxation degree of the rock mass; based on the obtained blasting relaxation rock mass model accommodating the blasting relaxation index, analysis of a relaxation rock mass specificarea or coupling analysis with a rock mass quality index or other rock mass indexes can be carried out.