Abstract: Three additives (combustion coal ash, coal gasification ash and oxide mixture) with similar chemical composition were added into petcoke by dry mixing and wet mixing. Their gasification reactivities under CO₂ atmosphere were investigated by a Thermo gravimetric Analyzer (TGA) at 1200-1400℃.The influence of mixing method, coal ash content and phase components on petcoke catalytic gasification was studied. The oxide mixture was used to simulate the catalytic effect of actual coal ash at high temperature. The results indicate that gasification reaction rate of petroleum coke is accelerated with increasing amount of coal ash. Dry mixing and gasification coal ash has less obvious effects on catalytic activity at 1200 and 1300℃. But the mixing method and mode of active metal has little influence on gasification reaction of petcoke at 1400℃. It is because the molten ash keeps good contact with petcoke, which makes reactive metals more freely and enhances mass transfer resistance. The catalytic index of the oxide mixtures has linear relationship with content of Fe₂O₃ and CaO during petcoke gasification at high temperature. This means coal ashes with high content of Fe and Ca could accelerate CO₂ gasification reactivity of petcoke.