The purpose of this study was to investigate the gasification properties of biomass chars obtained under different conditions by using non-isotherm thermogravimetric method. The physical and chemical structure features were also systematically studied. It shows that the gasification reactivities decrease with increasing pyrolysis temperature, and the gasification reactivities for the chars obtained under different atmosphere conditions are in the order of N2 char > CO2 char > CO char > H2 char. The gasification reactivities of the chars are mostly depend on the carbonaceous structure. Three nth-order represented gas-solid models, i.e. Random pore model (RPM), Unreaction core model (URCM) and Volumetric model (VM), were used to describe the reactive behaviors, and it indicates that the RPM is more suitable than the other two models.