Two types of activated carbon for the removal of element mercury in simulated flue gas were studied in the paper. Mercury adsorption process on fixed bed reactor has been researched. The conclusions are as follows: The trend of mercury concentration first decreased and then increased over time; as for two types of activated carbon, the adsorption corresponds to pseudo-first-order equation and pseudo-second-order equation respectively. Because of the high correlation coefficient, the pseudo-second-order equation will correspond to actual adsorption process.