A waterborne nitrocellulose (PWNC) emulsion modified by Polyacrylic grafting copolymerization was prepared by selfemulsification with nitrocellulose(NC) 、acrylic acid(AA) 、hydroxypropyl acrylate(HEPA) and hexamethylene diisocyanate(HDI) as main raw materials. Then, the corresponding PWNC films were obtained. Fourier transform infrared spectroscopy (FTIR), contact angle measuring instrument, transmission electron microscope (TEM), thermal gravimetric analyzer (TGA) and nano particle surface potential analyzer were use to characterize the chemical structure, hydrophobicity, particle morphology, thermal properties of PWNC films and the particle size of PWNC emulsions. The effects of dosage of DBTDL, mole ratio of AA to HEPA on the properties of emulsion and film were also studied. The results showed that the PWNC emulsion was stable and the particles of emulsion were regularly spherical with a core-shell structure. When the mole ratio of AA to HEPA to HDI was 3∶1:0.75 and the NC was 3.6g, the PWNC emulsion exhibited smaller particle size and narrow particle size distribution. Theaverage particle size and polydispersity index(PDI) were 52 nm and 0.021. respectively. The contact angle of modified PWNC films increased to 122.5? , Which indicated that the modified PWNC films had better water resistance than the NC films.