Objective To develop a highly stable camellia oil nanoemulsion system for loading grape seed polyphenol (GSP) to enhance its antioxidant property and solubility stability.Methods The formula is optimized based on the pseudo-ternary phase diagram method (m_{oil phase}∶m_{surfactant phase}=8∶2, m_{Tween 80}∶m_{Span 80}=5∶5, absolute ethanol is used as the cosurfactant, and Km=4). The emulsion stability and water distribution are characterized by Zeta potential and low-field nuclear magnetic resonance, and its antioxidant activity is evaluated.Results The obtained W/O nanoemulsion has a particle size of (326.5±2.7) nm, an absolute value of Zeta potential of (46.4±0.2) mV, a polydispersity index (PDI) of 0.238, and an electrical conductivity of 4.8 μS/cm. When loaded with 1.5% GSP, the proportion of free water decreases to 17.21%, and the scavenging rates of DPPH free radicals and ABTS free radicals are 82.69% and 71.18%, respectively. After centrifugation (10 000 r/min), high temperature (90 ℃), low temperature (-4 ℃) and 30-day storage, there is no stratification, and the light transmittance is >95.8%.Conclusion This system combines high biological activity retention with long-lasting stability.