The hot ductility of a Ti-bearing microalloyed steel was studied at temperatures of 600 to 1350℃ by a thermal simulator Gleeble 1500. The fracture morphology and microstructure were observed by scanning electron microscopy and optical microscopy. The precipitate behavior of second phase particles was calculated by the thermodynamic software Factsage. The hot ductility curve shows that SS400B steel with additional titanium has very good hot ductility during all the tested temperature range, and all the values of reduction in area are larger than 45%. Alx Tiy Oz generation at high temperature can act as nucleation sites for dimples to promote the ductile fracture. The amount of detrimental AlN can be reduced due to the formation of Alx Tiy Oz and TiN. Intergranular ferrite and cementite promote the intergranular brittle fracture.