Starch nanoparticles (SNPs) were prepared by rapid nanoprecipitation using coarse cereal starches, including quinoa, waxy proso millet, non-waxy proso millet, and maize starches (amylose content, 2.20 %-13.96 %). Morphology and dynamic light scattering analyses showed that the particle size of SNPs ranged from 190.35 nm to 310.25 nm. Ultrasonic pretreatment reduced the particle size. Quinoa and waxy proso millet SNPs swelled to flocculent, whereas non-waxy proso millet and maize SNPs showed spherical particles. Quinoa and waxy proso millet SNPs did not completely nucleate after nanoprecipitation. Quinoa SNPs formed a stable network in water, showing great viscoelastic behavior with higher G' and G''. Subsequently, the SNPs suspensions were used to prepare emulsions. The quinoa SNPs-based Pickering emulsion was the smallest and most uniform (12.96 μm), with great stability. These results suggested that the quinoa SNPs suspension with a stable network could be used as an efficient emulsifier for stabilizing Pickering emulsions.