Oil-in-water algae oil nanoemulsions (EAE-nano) containing small lipid droplets (d<100 nm) stabilized by sodium caseinate (SC) were fabricated via high-pressure homogenization and solvent (ethyl acetate) evaporation, while oil-in-water algae oil emulsions (AE-nano）were prepared by high-pressure homogenization as control. EAE-nano appeared to be translucent, but AE-nano was opaquein at the same oil concentration (1% algae oil). The properties of EAE-nano and the effects of pH, ionic strength (0~00 mmol/L NaCl) and thermal processing on the stability of EAE-nano were examined by dynamic light scattering technique. At pH 7.0, the mean particle size of EAE-nano was 76.8±0.5 nm, AE-nano was 180.9±2.1 nm. The effects of pH, ionic strength (0~00 mmol/L NaCl), thermal treatment (boiled 15 min) on the stability of the nanoemulsions and conventional emulsions were examined. The results indicated that EAE-nano had better stability to droplet aggregation and creaming than AE-nano. These results have important consequences for the utilization of food-grade nanoemulsions in beverage industries and encapsulating lipophilic functional components.