There are many types of shells in the world of biology such as various egg shells, conch shells, tortoise shells and skulls of human, all of them are one kind of thin shell structure with uniform curvature and lightsome of texture. This structure is not only light but also has a good pressure resistance. The composition, microstructure, and three-point bending properties of the turtle shell are studied in the paper. The results show that the turtle shell is composed of the element of Ca, P, C, Cl and Na etc. There are many pores in the turtle shell, and the cortical outer layer and spongy inner layer with collagen fiber winding. The middle layer with many pores absorbs energy and lower the load when acts on it. Therefore, the shell can protect the soft tissue of turtles. The multi-layer and porous structure will provide basis for design of biomimetic such as lightweight composite damping materials.