Stronger (0001) basal plane textures mainly include two types: and in AZ31 magnesium alloy thin sheet were formed after hot-rolling. The texture types of hot-rolled AZ31 magnesium alloy thin sheet after annealing at 523K and 673K respectively were as same as that of hot-rolled thin sheet without annealing, but texture intensities became weaker, especially after annealing at 673K. The strong texture of hot-rolled thin sheet caused anisotropy of mechanical properties (tensile strength b, yield strength s and elongation ) significantly , and the anisotropy reduced with the decrease of texture intensity after annealing. Besides texture, the grain shape also effects anisotropy of mechanical properties. The anisotropy becames more significantly with the increase of relative difference of grain diameter between transverse and longitudinal directions.