Abstract: Ore fragmentation is an important factor to consider when using block caving method. Based on the basic principle of primary fragmentation prediction using block caving method, a primary fragmentation prediction software system is developed using C++language on the DIMINE software platform. The system comprehensively considers the influence of spatial geometric parameters of the joint system and the in-situ stress, supporting the analysis of primary fragmentation prediction results from different perspectives such as block volume, equivalent size, and block shape. Taking a porphyry copper deposit abroad as an example, the software is used to predict the primary fragmentation of the ore body according to the exploration line zoning, and the results are compared and analyzed with the prediction results of commonly used BCF software at abroad. The results show that the oversize rate of primary fragmentation between the exploration lines of the ore body ranges from 40.8% to 74.8%, and the equivalent size varies between 1.65 m and 2.63 m. The predicted results of the software are relatively close to that of BCF software, and the trend of change is basically consistent. The predicted results provide a reference basis for the subsequent mining design of block caving mines.