Abstract: Mannose-specific lectins are widely distributed in higher plants and are believed to play a role in recognition of high-mannose type glycans of foreign microorganisms or plant predators. In this paper, we simulated the amino acid residue’s structural character of the sugar binding sites of mannose-specific-binding plant lectins, and calculated and analyzed solvent accessible surface area of the related residue and mean hydrophobicity of the surface patches. Results indicated: (1)Before the plant lectins bind sugar, their conformational variety are consistent; (2)The plant lectins exhibit the structural diversity, which may relate with the diversity of their biological function; (3)During the process of binding sugar, the surface part conformation of the plant lectins can have some variety; this kind of variety may benefit to recognize the plant lectins to the different sugar and bind the differently foreign glycoconjugates, and develop their defense function. To same family plant lectins, although their sequences have high homology, the biological functions have strongly diversity. The structural diversity of mannose specific plant lectins associated with the specific recognition of high mannose type glycans highlights the importance of mannose specific lectins as recognition molecules in higher plants. All results suggest: For biological macromolecule, the function is same, the structure is uncertainly similar; and the structure is similar, the function is uncertainly same.