The effect of mineral matters on the thermal decomposition of Jimsar oil shale was investigated through the TG-MS test to raw, carbonate-free, silicate-free and pyrite-free oil shale samples. The pyrolysis experiments were performed at different heating rates (3, 5, 10, 15 K/min) up to a temperature of 1000 degrees C. The results show that the mineral matters have no important effect on the pyrolysis reactions of kerogen in Jimsar oil shale, and the activation energy distribution of raw oil shale is almost identical to that of the demineralized oil shale samples. But, removal of minerals has some effect on the secondary reactions of the derived compounds during diffusing out of oil shale particles, consequently influencing the composition of the pyrolysis products. And the MS data shows that pyrites can react with organic matter to form H2S and SO2 at the temperature range of 510 to 650 degrees C. (C) 2016 Elsevier B.V. All rights reserved.