Abstract: Waterborne cationic polyurethane (WCPU) was prepared and blended with wheat gluten (WG) in solution. The blend powder of WG/WCPU was obtained by freezedryer and thermally compressionmolded to form a blend sheet. FTIR was used to analyze the secondary structure of the WG/WCPU blends. The absorption in the amide I of wheat protein was separated by least squares curve fitting. The results show that the hydrogenbonding of β sheets in WG decreases firstly, and then increases with increasing the content of WCPU in blends. The hydrogenbonding was weakened by WCPU, and the WG/WCPU blend sheets were plasticized. The water uptake of the blend sheets is a Fick’s process, and the water diffusion in the sheets is predominant. Scanning electron microscope (SEM) images of the WG/WCPU blends reflect the fact that the blending of WG and WCPU is effective and homogenous.