Carbon nanotubes are ideal candidates for the mechanical reinforcement of ceramic due to their excellent mechanical properties, high aspect ratio and nanometer scale diameter. In this study, the effects of multi-walled carbon nanotubes (MWCNTs) on the mechanical properties of diopside (Di) scaffolds fabricated by selective laser sintering were investigated. Results showed that compressive strength and fracture toughness improved significantly with increasing MWCNTs from 0.5 to 2 wt %, and then declined with increasing MWCNTs to 5 wt %. Compressive strength and fracture toughness were enhanced by 106% and 21%, respectively. The reinforcing mechanisms were identified as crack deflection, MWCNTs crack bridging and pull-out. Further, the scaffolds exhibited good apatite-formation ability and supported adhesion and proliferation of cells in vitro.