The apparent characteristics, mass loss and mechanical properties of ultra-high performance concrete after exposure to high temperature were studied through the high temperature heating test and the cubic compressive strength test. The effects of steel fiber, polypropylene fiber, steel fiber and polypropylene fiber on cracking suppression of ultra-high performance concrete were compared. The effects of temperature, fiber type and content, aggregate (quartz sand and steel slag) on the strength of ultra-high performance concrete were investigated. The test results show that 1% steel fibers and 2% polypropylene fibers can effectively restrain high temperature explosion behavior, and the specimen remains intact after high temperature. Ultra-high performance concrete with steel slag aggregate and hybrid fiber has excellent high temperature mechanical properties, the residual strength of 67% can still be maintained after being exposed to high temperature at 1 000℃. With the increase of temperature, the cubic compressive strength of ultra-high performance concrete increases first and then decreases. High temperature enhances the compressive ductility of ultra-high performance concrete when the target temperature is more than 600℃.