Abstract: In this work fatigue behaviors of steel honeycombsandwich beams at high temperature are investigated through three-pointbending tests. The results show that fatigue properties are significantlyinfluenced by different core configurations. Specimens with W-direction arefit for fatigue loads. A fatigue modulus reduction approach is adopted whichis based on the interpolation by the empirical functions of experimentalresults, whose coefficients depends on the material properties and loadingconditions. This approach permits to predict the fatigue life of the steelsandwich structures while avoiding a large number of experiments. Theresults show a second-order polynomial function is fit for describingresidual modulus degradation rules of L-direction specimens, whileexponential function for W-direction specimens. Two non-linear cumulativedamage models, derived from the chosen stiffness degradation equation, areexamined in context with the linear Miner damage rule and compared withexperimental results. The developed models give a reasonable explanation forthe damage of steel honeycomb sandwich beam under high temperature.