Abstract: The microstructure and mechanical properties at room temperature of AZ31 magnesium alloy plate were analyzed by optical microscope（OM）, scanning electron microscope（SEM） and tensile testing machine before and after bending and limited width straightening. The results show that after bending and limited width straightening for initial board,a large number of tensile twins appear in sample and their ratio reaches 30%. Also, the grain size decreases obviously. After bending and limited width straightening, the texture changes from the typical（0002） basal texture to rotating to RD direction.Besides, both the tensile strength and elongation of the plate after bending increase, the yield strength decreases, the plasticity improves.