Doogh is a fermented drink produced from milk originated from Middle East as well as Iran. Recently this product with high nutrition value encounter to increasing consumer demand. However, over activity of micro-organisms that are naturally present in doogh causes souring and swelling. Furthermore, contamination and spoilage can occurre due to molds and yeasts. Phase separation because of aggregation and precipitation of proteins under low pH is also another problem of its production. Various methods were used to preserve food products and increasing its shelf life. One of the best methods for dairy products is spray drying. In this study spray drying was used to produce doogh powder with tragacanth and high methoxyl pectin as the natural hydrocolloids. Yoghurt produced from skim milk, water, maltodextrin (as coaid-dryer) and edible salt were mixed in proportions of 60%, 34.3%, 5% and 0.7%, respectively. After final fermentation, produced doogh was dried in experimental scale using a mini spray dryer. The effects of inlet temperature (100-140 o C) and gum (tragacanth, pectin and without gum) were investigated on moisture content, bulk density, solubility, flowability, cohesiveness, porosity, pH, color, and phase separation. Results indicated that temperature increasing significantly decreased moisture content and color, while, increased phase separation. Also, the effect of gum type on bulk density, solubility and phase separation were significant. Pectin containing treatments had the highest bulk density. Treatments containing gum had higher solubility than blank treatments. Serum separation of treatments with tragacanth was less than treatments with pectin and blank treatments. Serum separation of treatments with tragacanth increased with temperature, while other treatments were approximately constamt. Drying conditions were optimized for ideal processing criteria using response surface methodology and d-optimal design. Results represented that drying at 122 o C with tragacanth was the best conditions for production of doogh powder. Under the optimum condition, moisture content, bulk density, solubility, carr index, phase separation, color (L factor), pH, hasner ratio and porosity were 5, 0.31, 88, 37, 65, 89, 4.33, 1.59 and 73.5, respectively. Sensory evaluation showed that doogh powder produced under optimum condition after reconstitution didn’t have significant difference with fresh doogh in taste, color, aroma, stability and total acceptance.