Pterostilbene, being extracted from many plants, has significant biological activities in preventing cancer, diabetes, and cardiovascular diseases so as to have great potential applications in pharmaceutical fields. But the poor solubility and stability of pterostilbene strictly restrained its applications. As a good protection and oral delivery system, an optimal nanoemulsion for pterostilbene was developed by using low-energy emulsification method. Systematic pseudo-ternary phase diagrams have been studied in optimization of nanoemulsion formulations. The prepared pterostilbene nanoemulsion was characterized by transmission electron microscope, Fourier transform Raman spectrum, and laser droplet size analyzer. Nanoemulsion droplets are circular with smooth margin, and the mean size is 55.8 ± 10.5 nm. The results illustrated that the nanoemulsion as oral delivery system dramatically improved the stability and solubility of pterostilbene, and in vitro release of pterostilbene was significantly improved (96.5% in pH 3.6 buffer; 13.2% in pH 7.4 buffer) in comparison to the pterostilbene suspension (lower than 21.4% in pH 3.6 buffer; 2.6% in pH 7.4 buffer).