Abstract: Disclosed is a folding device, comprising: a first folding part, configured to fold, for a first time in a first direction, a folded object in half; a second folding part, configured to fold for a second time in a second direction in half, the folded object that has been folded in half for the first time, wherein the first direction is opposite to the second direction; a third folding part, configured to fold, for a third time in a third direction, one end of the folded object that has been folded in half for the second time, wherein the third direction is perpendicular to the second direction; a fourth folding part, configured to fold, for a fourth time in a fourth direction, the other end of the folded object that has been folded in half for the second time, where the fourth direction is opposite to the third direction.