To study the fracture properties of steam-cured concrete under different curing temperatures， three-point bending （TPB） specimens at different curing temperatures （20， 45， 60， 80 and 95 ℃） were tested. Based on the double-K fracture theory， the effects of curing temperatures on the mechanical and fracture properties of the steam-cured concrete were analyzed， and the relationship between the damage factor of concrete and the loss ratio of fracture toughness was discussed. The results indicate that the mechanical properties and fracture properties of concrete under 45 ℃ curing condition are consistent with that under 20 ℃ curing condition； when the curing temperature is higher than 45 ℃， the thermal damage effect enhances， and the fracture parameters of the specimen（ including initial fracture toughness， unstable fracture toughness， fracture energy and characteristic length ）decrease with the increase of curing temperature； a good correlation between the loss ratio of fracture toughness and the strength damage factor defined by elastic modulus or compressive strength is observed， which provide a basis for the fracture parameters of steam-cured concrete.