Abstract In this investigation, the dynamic compression tests of 25 vol% and 55 vol% B4C/2024Al composites were conducted in a wide range of strain rates (1000–5000/s) and temperature (298–723 K). The true stress-true strain curves show that the composites have obvious strain softening during plastic deformation. And damage degradation is the main cause of strain softening. A modified Johnson–Cook model including strain softening term was proposed. A comparative study was made on the accuracy of the classical and modified Johnson–Cook model to predict the flow stress. The results indicate that the modified Johnson–Cook model can more accurately estimate the flow stress of 25 vol% and 55 vol%B4C/2024Al composites.