Starch is one of the staple foods of human beings. The long-term use of foods containing rapidly digestible starch can easily induce chronic syndromes such as diabetes and obesity. Slowly digestible starch and resistant starch can control and prevent these syndromes. Proteins are another major nutrient of human diet. It can interact with starch， affect the digestibility of starch， and then affect the rise of postprandial glycemic glucose. In this study， the effects of oat protein， quinoa protein， black bean protein and lentil protein on wheat starch in vitro digestion and glycemic index were studied. The inhibition of four exogenous plant proteins on α-amylase and α-glucosidase were further investigated. The results showed that the four exogenous plant proteins could significantly reduce the hydrolysis rate and glycemic index of wheat starch， reduce the content of RDS and increase the contents of SDS and RS. Oat protein and quinoa protein had a greater impact on the content of RDS， and black bean protein had a greater impact on the content of RS. In addition， oat protein， quinoa protein and black bean protein decreased α-amylase activity. Among them， black bean protein had the greatest inhibition effect on the activity of α-amylase. Effects of black bean protein and lentil protein had the inhibition effects on the activity of α-glucosidase was inhibited， and the inhibitory effect of lentil protein was greater than that of black bean protein.