Weathered coal can be used for passivation remediation of heavy metals in farmland soil because it can chelate heavy metals with its active functional groups and reduce the mobility and bioavailability of heavy metals in soil. This study studied Hg adsorption characteristics of weathered coal and the radial migration and bioavailability of Hg in soil. The results showed that pH had little effect on Hg adsorption capacity due to the buffering of weathered coal, the maximum adsorption capacity was 8.19 mg/g. Hg adsorption of weathered coal was endothermic reaction, could be described well by Freundlich equation while the adsorption kinetic could be described well by pseudo-second-order rate equation. Hg content in leaching solution was decreased by 2.62, 1.66, 1.10, 0.70 μg/g, respectively when added weathered coal was 1, 2, 4 and 8 g into soil column, indicating weathered coal could reduce Hg migration from soil to solution. Pot experiment further proved weathered coal could prevent Hg migration from soil to plant, compared with CK, Hg concentration in cabbage leaves decreased by 400.00 mg/g and 0.09 μg/g in treatment 1(gellow soil added weatherad coal) and decreased by 0.31μg/g and 0.33 μg/g in treatment 2(yellow soil added weathered coal and Hg) when the cabbage was planted after 30 days and 70 days. Generally, weathered coal, as an efficient, environment-friendly and cheap material, can absorb Hg in soil and prevent its migration from soil to plant without any secondary pollution, thus provides a new strategy of the remediation of heavy metal contaminated soil.