Abstract: To investigate the changes in the structure of petroleum coke and coal after rapid pyrolysis under the condition similar to the practical coal gasifier, two kinds of petroleum cokes and one bituminous coal were pyrolyzed in a drop tube furnace at 800~1 400℃. The structure of petroleum coke and coal were characterized by using surface area porosity analyzer and XRD (X-ray diffraction) analyzer, the CO₂ gasification reactivity of samples was examined by TGA (thermogravimetric analyzer). The result shows that the pore in petroleum coke is mainly micropore compared with coal; with the increase of pyrolysis temperature, the micropore surface area of petroleum coke and coal increases first and then decreases gradually. Rapid pyrolysis lowers the graphitization degree of petroleum coke and coal. The changes in the carbon crystallite structure for petroleum coke are mainly observed in the average stacking height, while the changes in the carbon crystallite structure for coal is manifested in the value of 2θ₀₀₂, interlayer spacing and average stacking height. Although the gasification reactivity changing tendency of petroleum coke and coal with the increase of pyrolysis temperature is different, the gasification reactivity is closely related to the carbon crystallite structure.