AZ31 magnesium alloy was rolled and annealed after rolling in this work. The anisotropy of magnesium plate in rolling state and annealed state was studied, and the effect of annealing on anisotropy was analyzed. The results showed that rolled magnesium alloys was anisotropic visibly and the difference of texture strength between different orientations of magnesium alloys decreased after annealing. The tensile strength, yield strength and elongation anisotropy index of annealed state magnesium plate were smaller than that of rolling state magnesium, especially in elongation, which displays that annealing can improve the anisotropy of Mg alloys .