Abstract: In polar resource development and high-latitude cold-region engineering, concrete structures are frequently subjected to the coupled effects of low temperatures and dynamic loading. To accurately investigate the mechanical response under these conditions, Split Hopkinson Pressure Bar (SHPB) tests were conducted within a temperature range of 20 °C to -20 °C to characterize the temperature- and strain-rate-dependent properties of concrete. Based on the experimental findings, an improved dynamic damage constitutive model was developed by incorporating a temperature coefficient into the damage evolution equation. This model was further integrated with the Equation of State (EOS) and the RHT yield criterion to fully account for low-temperature effects. The proposed model was numerically implemented via a Fortran-based Vectorized User Material (VUMAT) subroutine. The accuracy of this user-defined model was rigorously verified by comparing numerical stress waveforms and fracture morphologies with SHPB experimental results. Finally, the validated model was applied to simulate projectile penetration into low-temperature concrete targets. The results demonstrate that low temperatures significantly inhibit penetration damage and reduce penetration depth. This phenomenon is attributed to the combined filling and bonding effects of pore ice, which enhance the target’s resistance to impact and large deformations. These findings provide a solid theoretical basis and numerical framework for the impact-resistant design and safety assessment of structures in cold regions.