The invention provides a method for measuring a coal seam liquid carbon dioxide phase-change cracking permeability increasing range. The method comprises the following steps that (1) the position of a cracking hole is determined, a plurality of groups of observation holes corresponding to the cracking hole are drilled around the cracking hole, and distances between the observation holes in the same group and the cracking hole are equal; (2) observation is conducted on each observation hole to obtain observation data; (3) after the obtained observation data are stable, the cracking hole is drilled, and then cracking is conducted; and (4) observation is conducted on each group of observation holes, and after-cracking observation data for evaluating the cracking permeability increasing range are obtained. An appropriate drilling arrangement form is designed in an experimental region firstly, the distances of the cracking hole and the observation holes present gradient distribution while extraction is not influenced, and monitoring of the changing situation in the observation holes of different distances and determining of the range of the permeability increasing effect are facilitated. The purpose of rapid promotion and use of carbon dioxide phase-change cracking in coal mining operation can be achieved.