Abstract: The potassium halide additive was added through kneading process to modify the activated coke. The scan- ning electron microscope and X-ray photoelectron spectroscopy were used to analyze the surface morphology,the kind of oxygen-containing functional groups and the relative content of oxygen-containing functional groups of the prepared activated coke. Using simulated flue gas,the mercury removal performance of the prepared activated coke samples was evaluated. The analysis found that the partial decomposition of potassium halide additive can improve the degree of ac- tivation,optimize the pore structure of the activated coke. Also,the potassium halide additive increases the relative content of the C—O functional groups in the activated coke. Compared with the blank sample of the activated coke,the relative content of the C—O functional groups in the three kinds of modified activated coke samples increase 13. 2% , 15. 2% ,15. 7% respectively. The mercury performance evaluation found that with the relative content of the C—O functional groups,the mercury removal performance of the activated coke is strengthened. Preparation of the modified activated coke by using potassium halide additive can effectively improve its mercury removal efficiency.