The pyrolysis characteristics of coal in cooling process of the high temperature molten tailings produced in copper slag smelting reduction process with both single coal and coal-slag mixture samples were studied by kinetic calculation, and XRD and meteorological chromatography analysis. The results showed that under the initial temperature of 1200℃ and cooling rate of 6.667 K/min, the maximum mass loss rate of coal increased, the corresponding time point ended before 6~7.5 min and final mass loss quantity increased 3.08%~6.3% with the coal-slag mixture compared with the single coal pyrolysis. The CaO component in the slag had dehydrogenation effect on the coal aromatic rings, leading to the increase of content of H2 in pyrolysis gas. Pyrolysis of both samples showed the first order reaction, and the activation energy of primary pyrolysis and gasification reaction of coal-slag mixture sample decreased compared with the single coal. But the main pyrolysis activation energy of coal-slag mixture increased compared with the single coal, because the reducibility in the main pyrolysis bed caused the reduction of high valence iron oxides. The increase of reaction types made the apparent activation energy become higher.