In this study, the effect of pre-deformation at recrystallization and non-recrystallization zone on the grain ultrafifining by the subsequent intercritical deformation (ID) was investigated on low-carbon microalloyed steel. The results showed that ultrafifine grain microstructure with an average size of * 1.0 lm was fabricated through pre-deformation in the recrystallization zone followed by ID. When pre-deformed at the non-recrystallization zone prior to ID, the grain size increased to 1.6 lm with a heterogeneous distribution along with the well-developed dynamic recovery of ferrite. The grain ultrafifining mechanism was attributed to the combined action of the deformation-induced ferrite transformation and the continuous dynamic recrystallization. In particular, the continuous dynamic recrystallization process during ID occurred on the pro-eutectoid ferrite as a result of the subgrain rotation mechanism and the absorbing dislocations mechanism.