Gum tragacanth nanoparticles was prepared in this research applying intense ultrasound energy followed by anti-solvent precipitation in ethanol. The results of optical microscopy, SEM images and spectrophotometry showed that smaller particles were produced by increasing sonication time. As well, increasing the ultrasonic power led to smaller particle production, however increased aggregation. On the other hand, 0.5 and 1% concentrations of tragacanth solutions were prepared and mixed with ethanol (ratio 1:10) after ultrasound treatment with two different drop-wise and direct methods. The nanoparticle images showed that the concentration of 0.5% tragacanth solution and direct mixing method were suitable conditions for particles production with desirable size and uniformity (72±10 nm). FTIR, XRD and STA studies showed that tragacanth nature did not change and only the particle size decreased. Investigation of the solution viscosities of 0.5% untreated tragacanth gum and tragacanth nanoparticles showed that the viscosity of the nanoparticles solution was significantly lower than that of the tragacanth solution with a similar concentration, indicating the intense effect of particle size reduction on this property. Investigation of wettability showed contact angle of 88.9±1.7 degrees for nanoparticles providing partial wetting of the particles at the interface of the two phases in the Pickering emulsions. In the second step of this research, Pickering emulsions were prepared using 0.5, 1 and 1.5% nanoparticles with the ratios of 10, 20, 30 and 40% of sunflower oil. Also, emulsions containing 0.5% solution of tragacanth gum were prepared as control. Results showed that the viscosity of the emulsions prepared by the nanoparticles was significantly lower than the viscosity of the control emulsions in each oil ratio. The viscosity of the emulsions was influenced by the concentration of nanoparticles and the oil ratio such a way that the viscosity of the emulsions increased by increasing the particle concentration and oil ratio. Microscopic images showed that in each oil ratio, the size of the emulsion droplets decreased with increasing the nanoparticles concentrations. Evaluation of the emulsions stability showed that changes of the average droplets diameter of emulsions stabilized with nanoparticles containing 10 to 30% oil was not significant after one-month storage at room temperature while, the size of droplet of emulsions stabilized with tragacanth gum increased over the 30 days of storage. Also, the droplets size distribution graphs in these emulsions had two or more peaks in contrast to the stabilized emulsions with nanoparticles. Investigation of emulsion stability during one month showed that the emulsions stability increased with increasing nanoparticles concentrations in a constant oil ratio. The gravity phase separation due to the centrifugal stress reduced by increasing the concentration of nanoparticles in a constant oil ratio. However, an oil layer was observed on the emulsion surface in addition to serum phase separation after the centrifuge stress in the emulsions stabilized with gum tragacanth, which its content was increased with the oil ratio increase. Also, the results of thermal stability confirmed the effect of the concentration of nanoparticles and the oil ratio on the stability of the emulsions. The use of tragacanth nanoparticles as a natural biopolymer is a promising approach in emulsion systems to prevent coalescence and to increase the stability in the Pickering emulsions. Keyword: Tragacanth gum, Nanoparticle, Pickering emulsion,‌ Ultrasonic, Anti-solvent precipitation