The Al sheet used for pressure can manufacture (or called Al piece) was prepared by different melt-treatment techniques and using the lower grade commercial purity raw Al (Al99.5). And the influence laws of melt-treatment techniques on the metallurgical quality and mechanical properties of Al piece were investigated. It is found that high-efficient melt-treatment technique improves the metallurgical quality of Al piece remarkably, that is, the rate of removing inclusions and the extent of lowering porosity amount to about 66.6% and 87.0%, respectively, and as-cast mean grain diameter decrease to a great extent, and the coarse and long needle/flake Fe-rich impurity phases transform into complex compounds of tiny, sphere/short stick form, which makes fracture mechanism of the material be transformed into the congregation of transgranular micro-hole, thus raising mechanical properties of this material remarkably. Its metallurgical quality and mechanical properties have reached or exceeded the level of present products. It is feasible that Al piece is made by using the lower grade commercial purity raw Al. The viewpoint that the purification is the fundamental and key process, i.e., the basic of modification and grain refinement processes, has been also further tested and verified.