H13-mod steel developed after optimizing the composition and heat treatment process exhibits good hardness and impact toughness and can be used as a shield machine hob. Based on the Avrami equation, the dynamic recrystallization (DRX) behaviour of H13-mod steel during hot compression was studied in the temperature of 900–1150 °C and strain rate ranges of 0.01–10 s?1. A DRX model and finite element software were used to study DRX behaviour of H13-mod steel. Significant DRX was found at both low and high strain rates. Electron backscatter diffraction and optical microscopy analyses found different DRX nucleation mechanisms at low and high strain rates under different deformations. At a low strain rate, the nucleation was dominated by the strain-induced grain boundary migration, whereas the subgrain coalescence mechanism was dominant at a high strain rate. Moreover, dynamic recovery occurred in both processes. In addition, it was easier to obtain small and uniform equiaxed grains at high strain rates than at low strain rates.