The high-temperature properties and microstructure of ceramic fiber reinforced ultra-high performance concrete (UHPC) were evaluated through compressive strength and scanning electron microscope (SEM) tests at various temperatures. This research delved into how temperature and fiber content affect the visible appearance, mass loss rate, compressive strength, and microstructural alterations of UHPC. The findings demonstrated that incorporating ceramic fibers leads to a reduction in the concrete’s mass loss rate. When the heating temperature is less than 400 °C, ceramic fibers are effective in decelerating the decrease in compressive strength. But as the temperature rises further, the hydration products in the concrete start to decompose at a faster pace. Due to the concurrent influence of pore pressure, thermal stress, and the radial tensile stress emerging from the differences in thermal expansion coefficients, the compressive strength of the ceramic fiber - reinforced Ultra - High Performance Concrete (UHPC) plummets rapidly. Nevertheless, at any given temperature, the compressive strength of the fiber - reinforced UHPC remains significantly greater in comparison to that of the non - reinforced UHPC.