Abstract: Water-soluble cellulose ethers (CEs) can form hydrogen-bonded polymer complex with poly(acrylic acid) (PAA). In this work, hydroxyethyl cellulose (HEC) and PAA were selected as receptor and donor of hydrogen bond, respectively, to prepare H-bonded film. Then, HEC/PAA film was post treated with other H-bonding donors, such as tannic acid, and other receptors, such as hydroxypropyl cellulose (HPC), methyl cellulose (MC) and poly(vinylpyrrolidone) (PVPON). The film composition and thickness changes were investigated. The film thickness increases after post-assembly treatment in MC, PVPON and tannic acid (TA) solution, and the third component successfully getting into the films can also be clearly observed from the FT-IR spectra. And when the film prepared with FITC labeled HEC and PAA is immersed into the solution of rhodamine B (RB) labeled HPC, HPC diffuses into the film while HEC diffuses out from the film. These results indicate that the post-treatment of the film with other H-bonding donor or acceptor polymers is a dynamic process, during which polymer chains diffuse into and out from the film. The post treatment will increase the film thickness and change the composition of the film, providing an approach to further modify the layer-by-layer assembled film.