The effects of adding non-dairy powder (5.00~100.00 g), ice (5.00~200.00 g), and sugar (0~12.00%, m/m) on the smoothness characteristics of milk tea, including particle size distribution, rheological properties, sensory evaluation, and oral soft tribology, were systematically investigated. A new sensory evaluation standard specific to milk tea smoothness was successfully established by supplementing and optimizing existing standards. The results showed that the amount of non-dairy powder added correlated negatively with particle size of milk tea and correlated positively with viscosity. The average particle size of milk tea was 0.66 μm when the amount of added non-dairy powder was 60.00 g. A prediction model and criteria for milk tea smoothness were established by oral soft tribology analysis of the samples. Specifically, when the oral soft tribological curve satisfied both K2∈(-0.23, -0.05) and vR2<40.00 mm/s, the milk tea exhibited optimal smoothness characteristics. Otherwise, the milk tea was bland or had a heavy mouthfeel, indicating poor smoothness. This oral soft tribology model demonstrated the ability to evaluate the smoothness characteristics of different formulations of milk tea, indicating that this technique has practical application prospects for rapid evaluation of the smoothness characteristics of fluid food products.