En-gene stainless steel folding door, including a doorframe having upper and lower guide rail and two left and right door leafs, having upper and lower guide idler, wherein the two door leafs and the left door leaf are hinged with the doorframe respectively, characterized in that the right door leaf is provied with an upper-lower lock whose spring bolts are insertable in the upper and lower guide rail respectively, the right side of the frame of the doorframe is provided with a slot in which the right door leaf is inserted upon closing, and the right door leaf is provided with a cover plate at its left side so as to cover the gap bewteen the left and right door leafs upon closing. The present utility model can open and close smoothly and occupies less space with beautiful appearance, and thereby can be used as dwelling house doors, and fire fighting passage doors.