Abstract: To investigate the effect of thermal treated whey protein on the quality of set yogurt,the texture analyzer was used to determine the gel texture of set yoghurt by adding coagulation yoghurt with pre-heat whey protein as a control,and found out the heat-induced whey protein with the proper degree. Using the texture analyzer and rheometer to research the effect of different heat-changed whey protein addition amounts and different sugar additions on the texture and rheological properties of set yoghurt. And combined with electron microscopy,the microscopic structure of set yogurt was observed to elect the better quality set yogurt. The results showed that adding 7% sugar and 0.30% thermal treated whey protein,which had been heated at 72 ℃ for 15 min,in the yogurt,the hardness of the prepared yogurt gel was(263.4±11.85) g,and the adhesiveness was(413.2±15.33) g·sec,and which the microstructure was significantly smaller and more evenly distributed compared with other set yogurt,the resulting network structure was more regular,compact and uniform. This showed that whey protein under this heat treatment conditions could be used as a food additive,which would have a important practical significance and reference value for the production of high-quality fortified yogurt.