To acquire Si 3 N 4 -based composite with combination of high mechanical properties and excellent electrical conductivity, dense multi-walled carbon nanotubes (MWCNTs)-dispersed Si 3 N 4 ceramics were fabricated, using BaCO 3 –Al 2 O 3 –SiO 2 (BAS) as a second phase to improve the density and avoid reaction between MWCNTs and Si 3 N 4 . The results revealed that 40 wt% BAS prominently benefited the densification of MWCNTs-dispersed Si 3 N 4 composites and promoted the phase transformation of α -Si 3 N 4 to β -Si 3 N 4 , thereby contributing to superior mechanical properties. Additionally, the effects of MWCNTs on the densification, phase transformation, microstructure and properties were investigated. MWCNTs were well dispersed without damage in BAS/Si 3 N 4 composites exhibiting excellent electrical conductivity. Consequently, these composites would be expanded to more applications including electrostatic chargeless bearing and electromagnetic interference shielding as well as high-temperature structural applications with geometrically complex morphologies.