In this paper, Ca-based sorbent, Ca(OH)2 and CaCO3, was modified with different concentration of KMnO4 and their mercury adsorption capability in the flue gas was experimentally conducted by using a lab-scale multi-phase flow reactor system developed by Shanghai University of Electric Power, and the result showed that the removal efficiency of flue gas mercury of Ca-based sorbent was greatly improved with modification by different concentration of KMnO4, and the removal efficiencies were 80.92%,85.38%,82.35%,83.51% and 89.84% respectively. The removal efficiencies of Ca(OH)2 modified with KMnO4 is increased significantly may be because strong oxidation of KMnO4 made Hg0 convert into oxidized mercury, Hg2 +, which is easier to be removed, as well as, the modification by KMnO4 may change the surface properties of Ca(OH)2 so that it became more active to capture mercury in the flue gas.