Wood-based flame retardant composites were fabricated based on vacuum-pressure impregnating method after high intensive microwave pretreatment. The effects of ammonium polyphosphate (APP) and modified nano-zinc borate (nZB) addition on flame-retardation and smoke-suppression properties of wood were investigated by cone calorimeter method (CONE) and thermogravimetric analysis (TGA). The results show that the heat release rate (HRR), peak heat release rate (pk-HRR), and total heat release (THR) of APP-treated woods decreased greatly with increasing concentration of APP. However, mean yield of CO...