The structure and mechanical properties of silica sponge spicule found in China Bo-hai were studied. The results show that this spicule has the complex hiberarchy: the first tier is nano silica particles; the second tier is the sub-rounds within one silica round; the third tier is silica rounds composed of several parallel sub-rounds; the fourth tier is homocentric round structure with alternant deposition of silica and organic matrix. The flexural strength of this spicule is 394.34GPa, the flexural modulus increases with the growth direction of rounds. The cross-sectional hardness is 2.933GPa, and the cross-sectional Yang’s modulus can reach 33.308GPa.