Abstract: The activation mechanism of petroleum coke with KOH at higher temperature was studied. Methods including SEM, XRD, pore structure analysis by adsorbing N2 and GC were employed during the study. The result showed that the petroleum coke was well activated at 750℃～800℃. The XRD result revealed that the product was mainly made of amorphous carbon partly graphited. The pore structure analysis showed that the products had a surface area of 2900m2/g－1 and the content of micropore over 90%. The CH4 volumetric adsorption was 115∶1. GC results showed that the gases produced during the activation were made up of H2, CO2, CO, CH4. According to the gas composition, the reactions probably taking place during the activation were put forward.