In order to study the flow behavior of Mo-14Re molybdenum-rhenium alloy at high temperature and its cross-scale characterization, the high temperature compression test of molybdenum-rhenium alloy bar was carried out with Gleeble thermal simulation testing machine, and the selected temperatures were 1400 ℃, 1500 ℃ and 1600 ℃. The strain rates are 0.01 /s, 0.1 /s, 1 /s and 10 /s. The results show that when the strain rate sensitivity factor increases gradually, the plastic flow performance of the material will be better, and the two phenomena of stress hardening and softening exist simultaneously during deformation. On this basis, a cross-scale constitutive model is established. The flow stress characterization takes into account the resistance, thermal activation and grain boundary effects of the immobile dislocation. The microstructure evolution takes into account the grain size, dislocation density, dynamic recrystallization rate and crack volume fraction. The calculated values of yield stress, grain size and flow stress are in good agreement with the experimental results. It can be seen that the model can describe the rheological behavior and microstructure evolution of Mo-14Re molybdenum-rhenium alloy during high temperature deformation.