<p>To investigate the evolution of microstructure during hot deformation of 38MnVS6 non-quenched and tempered steel, isothermal compression tests were carried out on a Gleeble-3500 thermal simulation machine. Based on the true stress–true strain curves, the hot deformation activation energy (<i>Qa</i>) was determined to be 352623.6 J·mol⁻¹. By coupling the peak stress model with the dynamic recrystallization (DRX) kinetic equation, a cellular automaton (CA) model was established, which involves the mechanisms of dislocation evolution, recrystallization, nucleation, and grain growth. The microstructure was characterized by optical microscopy (OM) and electron backscatter diffraction (EBSD). The effects of deformation parameters on grain size, DRX volume fraction, and grain boundary characteristics were systematically analyzed based on kernel average misorientation (<i>KAM</i>) and grain boundary (GB) distribution. The results show that increasing deformation temperature or decreasing strain rate significantly promotes DRX, leading to larger grain size and lower peak stress. With the increase in strain, the parent grains are refined, while the DRX volume fraction increases continuously. The average error between experimental data and CA simulation results is less than 5%, which verifies that the proposed model can accurately predict the hot deformation behavior and microstructure evolution of 38MnVS6 non-quenched and tempered steel. This study can provide a theoretical basis for the optimization of its hot working processes.</p>