Abstract: In order to study the effect of tectonic deformation for porosity development degree and structure characteristics of coal, mercury injection experiment was carried out on coal samples with different tectonic deformation degree. Total intrusion volume, porosity, median pore diameter, retro-mecurometric efficiency, saturation median pressure, as well as the characteri stics of pore size distribution and pore morphology were analyzed.The comparison of coal with different tectonic deformation degree was made, and they were also compared with the primary structure coal. According to the experiment, it can be shown that as tectonic deformation degree deepening, the total intrusion volume, porosity, median pore diameter increase gradually, and「 etro-mecurometric efficiency and saturation median pressure decreases, mesopore and macropore increases, and the changes of micropore and transition pore are no significant; the proportio n of micropore is reduced, mesopore increases, the proportion of transition pore and macropore accounted does not change obviously quantity of open-type pore increase, and the quantity of semi-closed pore is reduced.