poly(N-isopropylacrylamide) (PNIPPAm) is a thermally sensitive polymeric material which exhibits large volume transition at temperatures around its lower critical solution temperature (LCST). To get a thermosensitive semi-Interpenetrating Polymer Networks(semi-IPNs), N- isopropylacrylamide (NIPPAm) was dispersed and synthesized with different crosslinking agent amount in thermoplastic polyurethane(TPU) solution. The resulting films were characterized in terms of swelling ration, surface contact angle, and scanning electron micrograph (SEM). The results showed that filming medium has great affect on the structure and swelling of PU/PNIPPAm composite film and the amount of crosslinking agent influents the miscibility of PU and PNIPPAm. Ethanol as filming medium makes the phase separation behavior of PNIPPAm insignificant in the films.