In order to study the damage mechanism of sugarcane leaf sheath under the action of elastic leaf-stripping elements in the leaf-stripping process of whole stalk sugarcane harvester, the sugarcane leaf-stripping machine was designed, and the damage process of the leaf sheath was photographed by high-speed photography. By analyzing the pictures, the result showed that three damage forms, the abscission of leaf sheath from stalk, leaf sheath torn and the separation leaf sheath from stalk were found. The damage mechanism under the action of elastic leaf-stripping elements was analyzed based on the construction of simplified mechanical model and mechanical properties of sugarcane leaf sheath. The elastic force applied on the leaf sheath by elastic leaf-stripping elements was the main force to make the leaf sheath damage. The different damage forms had relations with growth character and mechanical property of leaf sheath. When the moisture content of leaf sheath was less than 20%, the abscission of leaf sheath from stalk was the main damage form. And the moisture content ranged from 20% to 50%, leaf sheath torn happened. Also the moisture content was greater than 50%, the separation leaf sheath from stalk appeared.