Abstract: The effect of deformation conditions on dynamic recrystallization behavior of Nb-V microalloyed HSLA steel was investigated via high-temperature single pass reduction tests on a Gleeble-2000 thermomechanical simulator, with some mathematical models developed for flow stress during hot deformation. It was found that the dynamic recrystallization occurs only at higher temperature and lower strain rate, and the peak strain/stress, steady strain and critical stress are all in linear relationship with lnZ. The prediction models developed for flow stress indicated that they are in good agreement with experimental results.