Based on the true stress–strain data obtained from dynamic compression experiments using split Hopkinson pressure bar, constitutive models including the Johnson–Cook model, modified Johnson–Cook model, Mechanical Threshold Stress model, and modified Arrhenius-type constitutive model are developed to describe the plastic flow behavior of GCr15 steel over a temperature range of 298 to 873 K and strain rates from 460 to 3940 s⁻¹. The material parameters for the models are optimized using the Grey Wolf Optimizer, and the predictive performance is evaluated based on the correlation coefficient and average absolute relative error. Furthermore, the micromorphology of the specimen after impact is observed using a scanning electron microscope. The results indicate that all four constitutive models effectively reflect the plastic flow behavior of GCr15 steel. The modified Johnson–Cook model is more effective and accurate than the Johnson–Cook model, Mechanical Threshold Stress model, and modified Arrhenius-type constitutive model for predicting the dynamic compression behavior of GCr15 steel, with a correlation coefficient of 0.9711, an average absolute relative error of 2.6501% and a mean relative error of −0.2899%.