In this work, the anisotropy variation of tensile flow stress for AZ31 magnesium alloys was investigated at various temperaturesand tensile strains with the help of the visco-plastic self-consistent model. The results showed that the anisotropyof flow stress was weakened with the increase of tensile temperature, while such anisotropy presented a slightly increasingstage first and then a continuously decreasing stage with the increase of tensile strain. During the tension deformation, theactivations of basal slip and tension twinning, together contributed to the development of a (0002)//LD (LD: loading direction)type texture. In contrast, the activations of prismatic slip produced a ⟨10–10⟩//LD type texture. Such texture variationsinfluenced the Taylor factors, but did not cause significant differences in the flow stress. By comparison, the difference inthe macroscopic average resolved shear stress, which was calculated according to the critical resolved shear stress of eachdeformation mode and their respective activation fractions, decreased significantly with the increase of tensile temperatureor tensile strain. This was the major reason for the decline of the tension deformation behavior anisotropy.