Abstract: In this study, the production process conditions of solidified purple potato yoghurt were optimized by orthogonal experiment and fuzzy comprehensive evaluation method taking fresh purple potato and whole milk powder as main materials. Results showed that the optimum processing conditions were determined as follows: purple potato juice addition of 87.5%, Streptococcus thermophilus and Lactobacillus bulgaricus content of 1%, white granulated sugar addition of 4%, fermentation temperature of 42 ℃, and fermentation time of 6.4 h. Under these conditions, the acidity and anthocyanin content of fermentative solidified purple potato juice yoghurt were 88.57 °T and 2.104 mg/g, respectively. The sensory score was 92.4 points. Besides, the yoghurt presented uniform texture,viscous taste, merged smell with milk mellow flavor and purple potato sweet flavor, bright color with lilac pink,which showed the best sensory properties.