Abstract: The flow deformation behavior and dynamic recrystallizations of austenite deformation and ferrite deformation of Ti+Nb stabilized ultra-low carbon bake hardening steel were studied by single pass hot compression test using Gleeble-1500 thermal simulator.The results show that Ti+Nb stabilized ultra-low carbon bake hardening steel is in the dual phase region at deformation temperature of 900℃.The softening of deformation metal and decrease of flow stress are induced by more and more softer ferrite due to phase transformation of austenite to ferrite.The dynamic recrystallization occurs with the strain rates of 1 s^-1,10 s^-1and 40 s^-1at deformation temperature of 700℃,while there is no dynamic recrystallization and only dynamic recovery occurs for the strain rate of 0.1 s^-1.Only dynamic recovery occurs with the strain rates of 0.1 s^-1and 1 s^-1over a temperature range from 750℃to 850℃,while the dynamical recrystallization occurs with the strain rates of 10 s^-1and 40 s^-1.The activation energy of austenite deformation of Ti+Nb stabilized ultra-low carbon bake hardening steel is Q_def=131984J·mol^-1.The dynamic recrystallization model of austenite deformation is \mathrmZ=\dot\varepsilon \exp (131984 /(\mathrmRT)).The activation energy of ferrite deformation is Q_def=268995 J·mol^-1.The dynamic recrystallization model of ferrite deformation is \mathrmZ=\dot\varepsilon \exp (268995 /(\mathrmRT)).