The Mg-Al-Zn-Mn-Ca magnesium alloy, after hot rolling, forms an elliptical texture, providing good application prospects. However, challenges such as poor symmetry, similar to basal textures, persist in elliptical texture formation. This study explores optimizing the texture of Mg-2Al-02Zn-0.4Mn-0.5Ca Mg alloy sheets using a hot rolling-shearing-bending (HRSB) treatment to improve their room temperature mechanical properties. The research systematically investigates structural evolution during the annealing process and the mechanism behind nonbasal texture formation, using EBSD, XRD, and other characterization techniques. The results show that after annealing at temperatures above 350 ^oC following hot rolling, the sheets develop an elliptical texture extending toward the transverse direction (TD). Following HRSB treatment and annealing at 400 ^oC annealing, the {\mathrm{10}\overline{\mathrm{1}}\mathrm{2}} extension twins generated during deformation remain uncrystallized, leading to an increase in the relatively symmetrical texture components between 20° and 70°. This also results in the formation of a ring texture. However, as the annealing temperature increases to 450 ^oC, the {\mathrm{10}\overline{\mathrm{1}}\mathrm{2}} extension twins nearly disappear, precipitation phases increase, and the nucleation of randomly oriented grains during recrystallization causes the circular texture characteristics to disappear. During the HRSB deformation process, the pyramidal <c + a> slip becomes significantly activated, dominating the primary dislocation density. The low-energy grain boundaries caused by the co-segregation of Al and Ca atoms at the grain boundaries, as well as the orientation gradient induced by the non-basal slip, jointly contribute to the formation of the non-basal texture.