Bio-mineralized carbon natotubes (CNTs) were prepared by soaking carboxyl functionalized CNTs in a simulating body fluid (SBF). A uniform hydroxyapatite layer was precipitated on the outer walls of CNTs after 7 days of soaking. The results showed that, by addition of the as-received CNTs and bio-mineralized CNTs, the compressive strength of the calcium phosphate cement (CPC) increased by 24% and 120%, respectively. The modified interfacial bonding between the bio-mineralized CNTs and CPC accounted for the significant improvement in the mechanical property by addition of the bio-mineralized CNTs as compared with the as-received CNTs.