To explore the temperature dependence of deformation behavior of BCC structural materials and the relevant effect of pre-annealing, commercially pure iron(CP Fe) produced by equal-channel angular pressing(ECAP) is selected as the experimental material. The influences of deformation temperature T and pre-annealing on deformation behavior,surface deformation characteristics and substructures of ECAP Fe were systematically studied. The results show that ECAP Fe undergoes a remarkable strain softening stage after a rapid strain hardening during uniaxial compression, and the softening degree and the yield strength rYSfirst decrease and then increase with raising temperature. Pre-annealing at400 °C effectively weakens the strain softening degree and increases rYS. To understand the influence of deformation temperature on deformation behavior, as well as the relevant pre-annealing effect, deformation and damage characteristics and dislocation structures are studied in detail. In a word, the strain softening of ECAP Fe is associated not only with internal structural instability, but also with temperature, and pre-annealing at 400 °C improves high-temperature mechanical properties of ECAP Fe. To explore the temperature dependence of deformation behavior of BCC structural materials and the relevant effect of pre-annealing, commercially pure iron (CP Fe) produced by equal-channel angular pressing (ECAP) is selected as the experimental material. The influences of deformation temperature T and pre-annealing on deformation behavior, surface deformation characteristics and substructures of ECAP Fe were systematically studied. The results show that ECAP Fe treatedes a remarkable strain softening stage after a rapid strain hardening during uniaxial compression, and the softening degree and the yield strength Pre-annealing at 400 ° C effectively weakens the strain softening degree and increases rYS. To understand the influence of deformation temperature on deformation behavior, as well as the relevant pre-annealing effect, deformation and damage characteristics and dislocation structures are studied in detail. In a word, the strain softening of ECAP Fe is associated not only with internal structural instability, but also with temperature, and pre-annealing at 400 ° C improves high-temperature mechanical properties of ECAP Fe.