Abstract: In order to improve the quality and safety of the solidified yoghurt, 1%, 1.5%, 2%, 2.5%, 3%, 4%, 5% whey protein powder (WPP) was added to the whole milk powder.In the production of yoghurt, the coagulation yoghurt without WPP was used as a control group, and the acidity, water holding capacity (WHC), syneresis sensitivity (STS), texture characteristics, rheological properties and microstructure changes of the yoghurt were measured and sensed.The effect of different amounts of whey protein powder on the quality characteristics of solidified yogurt was evaluated to determine the optimum amount of WPP. The results showed that, with the increase of the amount of whey protein powder, the titration acidity, water holding capacity, total number of lactic acid bacteria, hardness, adhesiveness, viscoelasticity and gelation of yogurt increased gradually, and the syneresis sensitivity (STS) decreased gradually. When the amount of WPP was 2%, the water holding capacity and viscoelasticity of yogurt significantly increased, the STS significantly reduced, and it had a better taste and a more continuous network structure. Compared with the control group, the overall quality was significantly improved.