In the entrained flow gasification process, char-ash-slag-liquid transition affected the gasification reactivity. Meihuajing bituminous coal (MB) and Xiaolongtan lignite (XL) were chosen to prepare raw and demineralized char, respectively. The gasification reactivity and char-ash-slag-liquid transition of raw and demineralized chars were characterized by thermogravimetric analyzer and in situ heating stage microscope, respectively. The results show that the higher the temperature, the greater the reactivity index R-0.9 of MB and XL raw and demineralized chars. At 1000 degrees C, char-ash transition occurred, and the reactivity and area shrinkage ratio of two raw chars were higher than those of the corresponding demineralized chars. At 1200 and 1300 degrees C, ash-slag-liquid transition occurred, and the difference of R-0.9 between MB raw and demineralized chars was negligible; however, the difference of reactivity index R-0.9 of XL raw and demineralized chars at 1200 degrees C was lower than that of 1300 degrees C. The inherent mineral has an important catalytic role to gasification reactivity. Moreover, the gasification reactivity difference between MB raw and demineralized chars is not as obvious as XL raw and demineralized chars for that the stable ash layer of MB raw char formed in the gasification process could increase the diffusion resistance. The pore collapse of XL raw char led to the exposure of the residual carbon on the surface of raw char which is helpful to the improvement of reactivity. Furthermore, the possible mechanism of char-ash-slag-liquid transition was proposed. The present study showed that char-ash-slag-liquid transition had great effects on gasification reactivity of coal char.