A cover for packaging and supporting a tablet computer has a lower casing for protecting a tablet computer; an upper cover rotatably connected to the lower casing for protecting the screen of the tablet computer from damage; the upper cover being formed with at least one foldable line area for folding the upper cover along the foldable line area wherein the upper cover is used as a cover and a supporter; the upper cover rotates along the lower casing with an angle greater than 180 degrees; the lower casing is folded along the foldable line areas so as to be formed as a supporter of the lower casing for supporting the tablet computer therein. Thus the computer can stand; and, the angle between the upper cover and the lower casing is adjustable so as to control the standing height of the tablet computer.