The cracking technology by liquid CO₂ transient has been increasingly applied to rock excavation. The rapid acquisition and systematic characterization of the fragmentation distribution have important application value for rapidly evaluating the effect of liquid CO₂ transient cracking under field conditions. In order to solve the problems of incomplete information acquisition, complicated operation, and large workload, a new method is proposed in this paper that combines the UAV camera technology and the MIPS image processing technology to comprehensively and quickly obtain the broken rock feature information (area, perimeter, maximum chord length, etc.) and apply it to liquid CO₂ transients. On this basis, through the comprehensive analysis of the inhomogeneity and curvature characteristics of the block information, the fractal theory was used to describe the distribution of liquid CO₂ transient fragmentation, and the fractal dimension D was applied to quantitatively characterize the fragmentation distribution of the broken rock. The field experiment results show that the “UAV camera + MIPS image processing” technology could extract the rock block information quickly, accurately, and completely. Moreover, the fractal dimension could better characterize the distribution of split block. The larger the fractal dimension was, the higher the proportion of small pieces was, and otherwise the lower it was. This study provides a new important technical support for timely analysis and rapid adjustment of borehole scheme and corresponding technical parameters.