A decoration includes a main body. The main body forms an outer edge portion and an inner edge portion. The outer edge portion is formed around a periphery of the inner edge portion. The inner edge portion has at least two disconnected coil cutting lines. The cutting lines equidistantly wrap around to a center of the main body and connect with each other, for the main body separately forming adjacent corresponded first convolution and second convolution by the cutting lines. By means of the convolutions being respectively pulled out toward opposite sides of the outer edge portion along an axial direction for positioning, making the convolutions respectively form conical revolutions at opposite sides of the outer edge portion, achieving tri-dimensional decoration.