Water-resistant films were obtained from polyurethane (PU)/nitrocellulose coating to regenerated cellulose films, which were prepared by coagulating cellulose cuoxam solution. The PU/nitrocellulose coating layer was cured at 80 degrees C for 2 min and formed semi-interpenetrating polymer networks (semi-IPNs) structure. The tensile strength (sigma(b)), water resistivity (R), water vapor permeability (P), and light transmittance of the coated films changed with nitrocellulose content in the coating, and the best values (such as sigma(b), 679 kg.cm(-2); R, 53%; P, 0.004 g.cm(-2).day(-1)) were attained at 33 wt % nitrocellulose. The TEM, EPMA, DTA, IRI and UV results-showed that the coated films have strong interfacial bonding, which is caused by covalent and hydrogen bonds between the cellulose film and the semi-IPNs coating. The biodegradation half-life t(1/2) of the coated films in soil at 20-30 degrees C was given to be 58 days, and after about 6 months the coated films were almost completely decomposed by microorganisms. SEM and the kinetics of decay studied on the biodegradability were discussed. The water-resistant films coated with PU/nitrocellulose have promising application where biodegradation is important.