Abstract: Molybdenum is a typical environmental sensitive element, and also a potential rare metal element. In order to find out the content characteristics of molybdenum in raw stone coal and coal ash and the migration rule between solid and liquid, stone coal and coal ash in southern Shaanxi Province were selected as the research object, and the molybdenum content in samples was analyzed by ICP-MS. To analyse the leaching rate of molybdenum from stone coal and coal ash in four different liquids, pure water, scid, alkaline and mine drainage were selected to simulate soaking experiment. The results show that the content of Mo is 315.4-785.4 μg/g in stone coal and 675.5-1 005.1 μg/g in coal ash, which shows that Mo tends to migrate to coal ash from coal after combustion. Different types of solutions presented different leaching rates of molybdenum in stone coal samples, and the overall characteristics were that the leaching rate of molybdenum in acidic solutions was generally lower than that in other three types of solutions. Different types of solutions also present different leaching rates of molybdenum in coal ash samples, and the overall characteristic is that the leaching rate of molybdenum in acid solution is higher, which is obviously different from that in stone coal samples. Further analysis of combined leaching amount shows that the acid conditions inhibited the emigration ability of molybdenum in stone coal, while the leaching rate and the leaching amount of stone coal ash in acid solution were generally higher than that in other solutions. It is believed that aerobic combustion results in the release of molybdenum from organic matter, the pyrolysis of molybdenum-containing ore, and the adsorption capacity of molybdenum resulted in the improvement of the migration capacity of molybdenum. The findings of the research have double guiding significance for environmental protection and extraction & utilization of molybdenum.