Texture evolution is strongly dependent on the deformation mode during thermo-mechanical treatments. In this paper, we report the texture evolution in a duplex Mg–Li alloy. The results provide an evidence of deformation mode transition in the hexagonal-close-packed (hcp) α phase with various thickness reductions. The activation sequence of deformation modes is basal slip first, and then pyramidal slip during hot-rolling to a thickness reduction of 40%. The relative activity of <c+a> slip decreases with further thickness reduction. After annealing, basal texture is strengthened and pyramidal component disappears due to static recrystallization and grain growth. The microstructure, specifically texture evolution in both hcp α and body-centered cubic (bcc) β phase and their effects on mechanical properties are quantitatively analyzed and assessed.