Abstract: The stress distribution of AZ31 magnesium alloy sheet during the bending and straightening process and its influence on the microstructure were studied.The results show that in the bending and straightening process, the stress of the sheet at the wave crest and the wave waist is different, resulting in different microstructure. More tensile twins will be produced at the corrugated waist, which will cut the grains, resulting in grain refinement and an increase in the tensile strength of the sheet after the bending and straightening.There is greater energy storage at the tensile twins to provide nucleation sites for recrystallization and produce more small grains. At the same time, tensile twins will cause changes in grain orientation, making it more conducive to slip.Therefore, the bending and straightening leads to the improvement of the sheet performance, and the microstructure of the wave waist plays a major role.