This　study　investigates　the　residual　mechanical　properties　of　steel-polypropylene　fiber　reinforced　ultra-high　performance　concrete　(UHPC)　subjected　to　elevated　temperatures　with　a　rapid　heating　rate,　including　cube　compressive　strength,　axial　compressive　strength,　flexural　strength,　stress-strain　curve,　and　elastic　modulus.　A　total　of　189　specimens　with　three　steel　fiber　contents　are　prepared.　According　to　experimental　results,　the　strength　of　UHPC　undergoes　a　strengthening　stage　as　the　temperature　rises,　and　decreases　after　exceeding　the　critical　temperature.　The　strength　of　UHPC　is　significantly　improved　with　increased　steel　fiber　content　below　400　°C.　However,　the　strength　enhancement　of　UHPC　by　steel　fibers　is　weakened　at　higher　temperatures.　Interestingly,　UHPC　exhibits　a　gentler　strength　change　at　the　rapid　heating　rate　compared　to　the　constant　low　heating　rate,　both　during　the　strengthening　and　degradation　stages.　The　calculation　formulas　for　the　mechanical　properties　of　UHPC　after　elevated　temperatures　are　established,　which　shows　a　good　agreement　with　test　results.　©　2025