Abstract: Ultra-high performance concrete (UHPC) is faced with problems such as high-temperature spalling and difficulty in post-damage strength recovery in engineering applications due to its extremely low water-binder ratio. One of the effective solutions is the incorporation of hybrid fibers and the application of secondary curing. In this study, steel-polypropylene (PP) hybrid fibers were used to improve the high-temperature volumetric stability of the matrix. The damaged specimens exposed to high temperatures of 300℃, 600℃, and 900℃ were separately subjected to spray curing with lime-saturated water and water-CO₂ cyclic curing. The mechanical properties and microstructures were evaluated through compressive strength tests, scanning electron microscopy (SEM), and mercury intrusion porosimetry (MIP). The results show that the hybrid effect of 3vol% steel fibers and 0.4vol% PP fibers effectively inhibited high-temperature spalling, ensuring a mass loss rate of only 8.62% for specimens after 900℃ exposure. This maintained the integrity of the UHPC matrix and provided a necessary carrier for strength recovery. During the repair phase, water-CO₂ cyclic curing demonstrated remarkable efficiency, achieving the same strength recovery level in just 7 days as 30 days of spray curing with lime-saturated water. Furthermore, it increased the residual compressive strength of the 900℃ specimens from 41.0 MPa to 81.5 MPa. Microstructural analysis confirmed that the water-CO₂ cycle induced a highly efficient mineralization reaction, where the generated calcium carbonate crystals and gel products jointly filled the thermal damage cracks, reducing the total porosity of the 900℃ damaged specimens from 20.5% to 5.0%. In summary, the combination of the physical crack inhibition of steel-PP hybrid fibers and the microstructural repair of water-CO₂ cyclic curing can effectively enhance the high-temperature resistance of UHPC and achieve the recovery of mechanical properties after thermal damage.