Perilla oil nanoemulsions, stabilized soybean protein isolated protein (SPI) -phosphatidyl choline, was prepared by using ultrahigh pressure homogenous technology. The effects of different SPI concentrations and ultrahigh homogenous pressures on stability of perilla oil nanoemulisons were researched. The results showed that with the increase of SPI concentration and ultrahigh homogenous pressure, the mean particle size and PDI were gradually decreased. The perilla oil nanoemulsions had the smallest mean particle size (230nm) and the lowest PDI value (0.15) under the condition of 4% SPI concentration and 140MPa ultrahigh homogenous pressure, which showed that the perilla oil nanoemulsions was homogeneous under this condition. After storage experiment for 21d, perilla oil nanoemulsions had strong physical stability by using Turbiscan stability analyzer and no change of mean particle size at 4% SPI concentration and 140MPa ultrahigh homogenous pressure. There was no fat separation or aggregation in the nanoemulsions with 4% SPI concentration and 140MPa ultrahigh homogenous pressure. The content of α-helix was decreased gradually but the content of β-fold and random coil were increased by using circular dichroism spectrum, which demonstrated that the change of the secondary structure of interfacial protein had a certain effect on the stability of perilla oil nanoemulsion. Study on the stability of perilla oil nanoemulsion provided a theoretical basis for the development of novel nano foods and the industrialized production of nanoemulsions. 