The char-CO2 reaction behaviour is important for oxy-fuel combustion of coal gangue and weathered coal or biomass. The thermal conversion characteristics of coal gangue, weathered coal, pine sawdust and their blends in CO2/N2 atmosphere were investigated using thermogravimetric analysis, focusing on the reaction behaviour of char and CO2. The results showed that the thermal conversion of coal gangue, weathered coal and pine sawdust all had two main stages, but pine sawdust had shorter time of thermal conversion. Mass loss of coal gangue/pine sawdust blends included two obvious stages with four overlapped peaks, which was different from coal gangue/weathered coal mixtures with two separated peaks. The addition of weathered coal or pine sawdust could improve the char-CO2 reactivity of coal gangue. However, the interactions were absent for all the coal gangue/weathered coal mixtures, and interaction between coal gangue and pine sawdust was obvious during the reaction of char and CO2, which was affected by the blending ratio of pine sawdust. [ABSTRACT FROM AUTHOR]