||Self-folding films are unique thin films its shape voluntarily changes by bending phenomenon due to expansion or contraction of the material if ambient environmental conditions change. However, inhomogeneous expansion/contraction is necessary to develop the properties of self-folding. For that reason, self-folding polymeric films can create bilayers structure by sequentially coating two or more polymers with different volumetric expansion characteristics. In this experiment, bilayer structure films were fabricated using polystyrene (PS) and poly(4-vinylpyridine) (P4VP) homopolymer and induced folding using the swelling characteristic when P4VP was exposed to acid. In addition, to check the degree of swelling of P4VP bottom layer, we adjusted the thickness of the films as well as UV cross-linking time, Hydrofluoric acid (HF) concentration and dipping time. As a result, we were able to systematically organize the conditions under which self-folding behaviors occur in PS/P4VP bilayer.