In the high temperature industry, controlling the external surface temperature of the kiln shell is crucial for reducing heat loss, energy consumption, and carbon emissions. While aerogels are esteemed for their superior thermal insulation properties and considered as optimal materials in the thermal insulation layer of energy saving lining for burning zone of cement rotary kiln, their structural integrity at elevated temperatures confines their applications to medium and low temperature settings. To overcome this limitation, the fiber-reinforced aerogel composites have been developed to bolster the high-temperature endurance of aerogel products. Notably, composites containing ZrO2-enhanced fibers exhibit significantly higher resistance to thermal degradation from local overheating, such as flame impingement, compared to their counterparts without ZrO2. However, the mechanisms of performance degradation and the reinforcing role of ZrO2 in fiber reinforced aerogel composites at high temperatures especially above 1000 °C, remain unclear. This study specifically focuses on the thermal conductive properties of commercial aerogel felts, both with and without the inclusion of ZrO2 across a range of temperatures, and examines the subsequent phase transitions and microstructural evolutions upon thermal treatment. Critical analyses of heat flow, mass change, density, linear shrinkage, and pore size distribution during the calcination process were conducted. After 6 h of heat treatment, composites with ZrO2-enhanced fibers retained an 81.44 % porosity, unlike composites without ZrO2 which sintered and became denser. The experimental findings demonstrate that the performance of fiber reinforced aerogel composites mainly depends on the fiber’s framework microstructure and fiber-aerogel reactions, which provides the references for developing excellent aerogel composites and evaluating of the usability in high temperature zone of kiln.