Due to the undesirable effect of direct use of spirulina on dairy products, it was decided to first remove the phycocyanin component from spirulina then added to the beverage yoghurt as a by-product. Also , Lactobacillus plantarum su . Plantarum PTCC 1896 was used instead of Lactobacillus bulgaricus strain and the ability of yoghurt to produce beverage was investigated. In this study, the phycocyanin pigment extracted from Spirulina microalgae, which lacks the unpleasant odor and taste of Spirulina, has valuable nutritional properties and high antioxidant properties as well as numerous therapeutic effects for the human body. Phycocyanin is one of the important bioactive compounds of Spirulina platensis . Dairy products, including yogurt, are a good bedding material for use in food products.Phycocyanin was first extracted by freezing-towing method and then purified by aqueous two-phase method. Subsequently, Lactobacillus plantarum strain PTCC 1896 was replaced by Lactobacillus bulgaricus strain to produce yogurt with probiotic properties. Each Lactobacillus plantarum and Streptococcus thermophilus strains were cultured individually according to the growth curve (up to 9 log cycles). After separation of bacterial sediments by centrifugation and washing, yogurt was added 1: 1 to milk. To produce probiotic yoghurt containing phycocyanin, the yogurt was diluted 1: 1 with water, then 0.2% CMC and 0.1% blueberry essential oil. Phycocyanin powder was added to various samples at ratios (0.2, 0.4 and 0.8 wt / wt%). In order to produce the product with favorable organoleptic characteristics and tastes of the consumers, the samples were divided into two groups containing sugar (5%) and salt (0.7%). The physicochemical and microbial properties of the beverage yogurt containing phycocyanin were then evaluated for 21 days. Studies showed that the pH of beverage yogurt containing phycocyanin was higher than that of control drink (yogurt without phycocyanin) and had a decreasing trend during storage. But the acidity has increased over this period. The viscosity of the samples showed that the samples containing phycocyanin and sugar had a higher rate than the control, which decreased during the storage period. Examination of the color of samples revealed that L * and a * index decreased with increasing phycocyanin percentage in the formula and did not change significantly during storage. The b * index also decreased with increasing phycocyanin ratio and increased during the storage period. Counting our strains of yoghurt showed that phycocyanin had no significant effect on growth or inhibition of bacteria. But during the storage period, the starter strains have experienced a decrease in the logarithmic cycle. Sensory evaluation of samples of yogurt containing phycocyanin and blueberry essential oil showed that the sample containing 0.8% phycocyanin and 5% sugar had the highest acceptance, even more than the control yogurt beverge (without phycocyanin and sugar) by consumers. Keywords: phycocyanin, drink yogurt, probiotic, Spirulina platensis