A thin PI film equal to or less than 200nm was fabricated on a Zr film to improve the mechanical characteristics of the latter. The PI film was prepared by two-step process. Througth fully reaction between Pyromellitic Dianhydride (PMDA) and Oxydianiline (ODA) in Dimethylacetamide (DMAC), polyamic acid (PAA) was produced. After the deposition of Zr film on floating glass using direct-current magnetron sputtering, PAA was prepared on the Zr film through dip-coating and then thermally imidized to form the PI film. The transmission spectrum obtained by using synchrotron radiation fits with calculation result fairly well. Although the combination of the PI film with Zr film results in the decline of the transmission, the mechanical strength of the composite film is improved, and the transmittances of the Zr(300nm)/PI(200nm) and Zr(400nm)/PI(200nm) films reach 14.9% and 7.5% respectively at 13.9 nm, still satisfying the actual requirement.© (2010) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.