Abstract: The real-time testing system of resistivity on coal containing gas under uniaxial compression were established where the resistivity changes of coal containing gas and coal not containing gas during the uniaxial compression were tested and analyzed, the gas mechanism was expounded. The research results indicated that the resistivity of the coal under two experimental conditions was presented to increase after the decrease；in resistivity decreasing stage, free gas played a delay effect on decrease of resistivity, which was that the rate of resistivity presented a trend of gradual decrease along with the increase of stress and it did not appear the phenomenon of sudden drop in the experiments of coal not containing gas; in resistivity increasing stage, free gas had a promoting effect on the increase of resistivity, which was that the stress level corresponding to resistivity at an "inflection point" was smaller than coal not containing gas, following the rupture in coal, increasing amplitude of the coal containing gas' resistivity was less than coal not containing gas generally.