Abstract: Three point bending(TPB) fracture toughness tests of weld zone and heat affected zone of Q460C structural high-strength steel with 14 mm in thickness at distinct low temperature points were carried out, and the fracture toughness values for weld zone and heat affected zone of the specimens were obtained.Then regression analysis with Boltzmann function was used, then the ductile-brittle transition temperature and its variation with temperature were acquired.The TPB fracture appearance was analyzed with the scanning electron microscope.The results showed that low temperature had obvious influence on the fracture toughness of weld zone and heat affected zone of Q460C steel.With the temperature decreasing, there was a downward trend on the fracture toughness.Moreover, the ductile-brittle transition temperature of weld zone is about -53.6℃, and that of the heat affected zone was about -40.3℃.Besides, the fracture appearances of weld zone and heat affected zone fractured at temperature point below -20℃ showed the brittle characteristics significantly.