Mesoscale simulations based on the resolved shear stress (RSS) analysis and the crystal plasticity finite element method (CPFEM) simulations were used to elucidate the deformation behaviors of E-form and AZ31 magnesium (Mg) alloys and the evolution of tension twin (TTW) and compression twin (CTW) variants during mini-V-bending. RSS analysis, which is based on the Schmid tensor, was used to calculate the type of twin variants and the number of TTW and CTW variants that evolved in the deformed Mg alloys. However, RSS analysis considers neither the critical resolved shear stress (CRSS) of twin systems nor the interaction with neighboring grains, and it failed to accurately predict the twin behaviors of deformed grains. This study simulated the spatial distributions of the relative activities of different deformation modes, accumulated twin fractions, accumulated plastic strains, and effective stresses via CPFEM. Compared with the RSS analysis, CPFEM simulation precisely explained the twin behaviors observed in both E-form and AZ31 Mg alloys. © 2018, The Korean Institute of Metals and Materials.