Abstract: Based on the analysis of hot deformation behavior, a twostage constitutive model of low carbon steel was developed. In the model, the effect of work hardening and dynamic recovery on the flow stress is described by a onestructure parameter model (dislocation evolution model); the softening effect of dynamic recrystallization is expressed by the Avrami equation. The model parameters are identified by using the experimental stressstrain curves obtained from the hot compressive deformation on Gleeble1500 thermosimulation machine, and then the variation of model parameters with deformation condition are investigated. The calculated flow stress curves agree well with the measured ones, which indicates that the developed constitutive model is applicable to the hot deformation process numerical simulation of the investigated low carbon steel.