Coal and biomass are regularly used in the preparation of activated coke. In this paper, coal and biomass (poplar bark) were co-pyrolyzed, and activated coke was prepared by physical “one-step activation,” followed by ammonization and additional activation by potassium carbonate (K2CO3). The activation temperature was set at 800 °C, the time was 60 min, and the activation atmosphere contained 10% steam and 20% CO2 by volume in nitrogen. The physical and chemical properties of activated coke prepared by “one-step activation method” and “two-step activation method” were compared. The mole fraction of ammonia was 5%, 10%, 15%, 20%, respectively, and the concentration of K2CO3 solution was 3%, 6%, 9%, 12%, respectively. It is found that the addition of ammonia can improve the physical and chemical properties and adsorption capacity of activated coke, but the increase of ammonia mole fraction has little effect on the activation reaction. The physical and chemical structure of activated coke impregnated with 3% K2CO3 solution was found to be well developed. The surface of the produced activated coke prepared by the above activation methods has abundant microporous structure and organic functional groups; hence, the final product is suitable to be used as an adsorbent in practical applications.