The invention discloses a preparation method for a single-layer cosmetic hose. The single-layer cosmetic hose comprises a hose body and a flap, wherein the hose body and the flap are integrally formed through injection; and the process of the integral injection forming is as follows: the flap is formed at first during the first injection, then the second injection is carried out in the case that the flap does not leave from a machine table, and the hose body is formed during the second injection, so that the hose body and the flap are integrally formed. The preparation method disclosed by the invention is capable of increasing the machining efficiency of the single-layer cosmetic hose and improving the machining quality of the single-layer cosmetic hose.