Uniaxial ratcheting and fatigue failure of tempered 42CrMo steelwere observed by the tests under the uniaxial stress-controlled cyclic loading with non-zero mean stress [G.Z. Kang, Y.J. Liu, Mater. Sci. Eng. A 472 (2008) 258-268]. Based on the obtained experimental results, the evolution features ofwhole-life ratcheting behavior and low-cycle fatigue (LCF) damage of thematerial were discussed first. Then, in the frameworkof unifiedvisco-plasticity and continuum damage mechanics, a damage-coupled visco-plastic cyclic constitutive modelwas proposed to simulate the whole-life ratcheting and predict the fatigue failure life of the material presented in the uniaxial stress cycling with non-zeromean stress. In the proposedmodel, the damagewas divided into two parts, i.e., elastic damage and plastic damage, which were described by the evolution equations with the same form but different constants, since themaximumapplied stresses inmost of loading cases were lower than the nominal yielding strength of the material. The ratcheting of the material was still described by employing a nonlinear kinematic hardening rule based on the Abdel-Karim–Ohno combined kinematic hardening model [M. Abdel Karim, N. Ohno, Int. J. Plast. 16 (2000) 225-240] but extended by considering the effect of damage. The maximum strain criterion combined with an elastic damage threshold was employed to determine the failure life of the material caused by two different failure modes, i.e., fatigue failure (caused by low-cycle fatigue due to plastic shakedown) and ductile failure (caused by large ratcheting strain). The simulatedwhole-life ratcheting behavior and predicted failure life of tempered 42CrMo steel are in a fairly good agreement with the experimental ones.