Abstract:Effect of water content in FDG gypsum on temperature rising characteristics under microwave heating was investigated. The results show that final heating temperature of FDG gypsum with 25% water content is higher than those with 20% and 0% water content. For FDG gypsum matching with anthracite and magnetite, either too much or too little water content hinders continuous rise of temperature within high temperature zone. Water in FDG gypsum can affect microwave selective heating and generation of hotspot for anthracite in mixture. The less content is the earlier anthracite will burn. For FDG gypsum mixture with 20% water content, rise of temperature of anthracite and hotspot at different time reduces possibility of abrupt change of heating rate, which prevents generation of thermal runaway and with better heating effect.