Isocyanate-terminated polyurethane was synthesized from polyethylene glycol and toluene disocyantes, which was used to modify the epoxy resin. D-230 was chosen as hardener to produce the PU/EP composite. The structure of composite was characterized by FTIR spectrum. Mechanical properties of the epoxy resin with different PU content were studied. Additionally, damping properties of the PU/EP composite were investigated using DMA, and the results showed that the damping properties of EP evidently improved by blending with PU and with the testing frequency increased, the spectra of tanδ-T shifted to higher temperature.