The cholesteric liquid crystalline structure in chitosan/polyacrylic acid composite films was studied by surfacetechniques. A periodical lamellar-like structure was observed in the permanganic acid etched film sufface by both scanningelectron microscopy (SEM) and atomic force microscopy (AFM)

instead of the thumb-print texture which can be detectedwith polarized optical microscopy. It is suggested that the periodical lamellar-like structure is induced by the etchingselectivity between cholesteric layers due to different molecular arrangement on the film surface.Four kinds of perpendicular disclinations

i.e. χ→τ-+λ+

χ→λ-+τ+

χ→τ-+τ+ and χ→λ-+λ+

were found in the composite films from SEM observations.The smallest periodicity of lamellar-like structure(equals to half pitch)is 20～40 nm measured with AFM.