Changes in vitro protein digestibility and contents of catchins in the system of tea polyphenol with milk protein was investigated.The results showed that in the model milk tea which contains 0.5 % milk protein and 0-10.0 g/kg tea polyphenols,the in vitro digestibility of the protein decreased as tea polyphenols content increased.It decreased significantly when the contents of tea polyphenols was more than 2.0 g/kg.When milk and tea mixed together at the same ratio and polyphenols was more than 2.5 g/L,the milk protein digestibility decreased significantly.The results also indicated that the interaction of tea polyphenols with milk protein was mainly physical interaction.The two catechins,EGCG and ECG had higher affinity with milk protein and had major affects on the in vitro digestibility of milk protein.