Abstract: In order to make Liquid CO2 Phase Transition fracture technology economical and efficient in antireflection zone, the crack initiation process is analyzed, and the mechanical equation is established by gas mechanics and fracture mechanics in this paper. And calculate the radius of influence in the NO.13 coal mine is 8.2m, the calculated results are verified by the field tests on the same time. In this paper, the study of the technology lay the foundation of the research of mechanism of the increase of the mechanism, technology parameters and other aspects.