Abstract: In this paper, we aim at the conformational change of the binding site when Concanavalin A complexes with different carbohydrates. We simulated the amino acid residue's structural character of the sugar binding sites of Concanavalin A, and calculated and analyzed solvent accessible surface area of the related residue. Results indicated: (1)There are many difference when Concanavalin A interacts with different carbohydrates; (2)Whichever carbohydrate does the Concanavalin A complex with, the major interactions with carbohydrates are offered by the Tyr12, Asn14, Asp208 and Arg228 of the binding site; (3)At the same time, it's vital that the first sugar ring's interaction with the binding site.