The effect of grain refinement on dynamic recrystallization controlled rolling(DRCR) of V-microallyed structural steel was performed in the temperature range of 750℃∼1000℃ and strain rate (ε˙) range of 0.1∼3.0/sec with decreasing temperature and increasing ε˙ pass strain of 0.3 and/or 0.5 by hot torsion. From the analysis of the values of the critical strain of ε_c for the initiation of dynamic recrystallization and the peak strain of ε_p, the relationship ε_c≒0.7ε_p was obtained. By increasing the pass strain from 0.3 to 0.5 at the penultimate pass in the DRCR schedule, dynamic recrystallization could be induced and accelerated the grain refinement.