A one-solution Layer-by-Layer (LbL) method through the assistance of diphenylamine-4-diazonium-formaldehyde resin (DAR) was used to fabricate the ultrathin organic films. In this method, small molecules were mixed with DAR in aqueous or organic solutions and a consecutive deposition of the glass plate into the solution can afford the formation of ultrathin organic films. This method not only reserves the advantage of conventional LbL deposition method but also can fabricate small compound into film. As examples, 4-(2'-thiazolylazo)-resorcinol and its metal complexes were successfully deposited into films through this onesolution LbL method.