A method for manufacturing a cover of an electronic device includes steps of offering a metallic green piece comprising a top plate, a bottom plate and a connecting plate interconnecting a side of the top and bottom plates; offering a profile molding insert and a lower mold, the profile molding insert forming a shaping surface, the lower mold defining a cavity to receive an end of the green piece; putting the profile molding insert in the green piece, the shaping surface of the profiling molding insert being oriented towards the end of the green piece; inserting the end of the green piece in the cavity of the lower mold and punching the lower mold to enable the top and bottom plates at the end of the green piece bent along the shaping surface of the profile molding insert toward each other.