The　effect　of　melt-treatment　techniques　on　the　mechanical　properties　of　the　aluminum　sheet　(or　called　＇aluminum　piece＇)　used　for　pressure　cans　is　studied　with　aids　of　tensile　testing　at　room　or　high　temperatures　and　SEM　analyses　of　the　morphologies　of　tensile　fracture.　It　has　been　found　from　the　study　that　main　metallurgical　defects　(such　as　inclusions,　porosity,　etc.　)　in　aluminum　piece　are　the　key　factors　of　making　the　mechanical　properties　of　the　material　not　be　brought　into　full　play,　and　also　the　main　sources　resulting　in　fracture　of　the　material.　High　efficient　treatment　of　molten　aluminum　can　improve　the　mechanical　properties　(especially　plasticity)　of　the　material　remarkably.　For　this　reason,　using　lower　grade　commercial　purity　raw　aluminum　for　production　of　aluminum　piece　is　feasible.