Effects of several key-processing factors on the viscosity of pasteurized yogurt were studied.The contents of Solid Non-Fat(SNF),addition of hydrocolloids and transferring,cooling,piping,filling and storage were optimized.The optimum values of the contents of SNF and hydrocolloids were 7.5% and 1.6% respectively.The rotational speed of transferring was 1 152 r/min,the pump output power was 15 m3/h,the best cooling temperature was 25℃.The best post-pasteurization was started 1 h after the transferring finished and the rotational speed was adjusted to 1 440 r/min with the pump power of 7 m3/h.The best storage condition was at 4℃ for 24 h before sales.After the optimization,the viscosity was increased by 77.0% and the product was moderate for viscosity meeting the requirement of room temperature sale.