The invention discloses a one-piece dress with a novel structure. The one-piece dress comprises an upper outer garment body, and a collar band which is arranged on the upper outer garment body, wherein a movable front piece and a movable rear piece are respectively arranged on the two sides of the collar band, a plurality of buttons are arranged on the movable front piece, button holes matched with the buttons are arranged on the movable rear piece, short sleeves, medium sleeves and long sleeves are respectively arranged on the two sides of the upper outer garment, the connection between the upper outer garment body and the short sleeves, between the short sleeves and the medium sleeves and between the medium sleeves and the long sleeves is realized respectively by using first zippers, first zipper pullers matched with the first zippers are arranged on the first zippers, six hems in red, orange, yellow, green, blue, indigo and purple are arranged at the lower end of the upper outer garment body, adjacent hems are connected through second zippers, and second zipper pullers matched with the second zippers are arranged on the second zippers.