In this paper, accelerated freeze-thaw tests and repeated loading tests on C40 and C50 concrete specimens were introduced to study the effects of freeze-thaw cycles on the mechanical performance of concrete under dynamic load. The test results showed that the mechanical performance of freeze-thaw damaged concrete under repeated loading decreased significantly and the characteristic curves of dynamic constitutive relation changed distinctly after freeze and thaw, the enveloping line and reloading curves before stress peak exhibited a concave shape due to the compaction effects, the strain hysteresis of unloading curve became more serious and the unloading curves tended to coincide gradually as the freeze-thaw cycles increased. The relationships between freeze-thaw cycles, strength grades of concrete and the characteristic value of stress-strain curve including mechanical properties parameters and constitutive model parameters were also studied to establish a dynamic constitutive relation for concrete with freeze-thaw damage.