Multi-walled carbon nanotube (MWCNT)-based carbon/carbon composites were fabricated by the chemical vapor infiltration of pyrolytic carbon into pre-compressed MWCNT blocks. The pyrolytic carbon was deposited on the surface of the MWCNTs and filled the gaps between the MWCNTs, which improved the connection between the MWCNTs and formed a three-dimensional network structure. The mechanical and electrical properties were improved significantly. The values of the maximum compressed deformation, maximum breaking strength, Young's modulus and energy absorption are measured as 10.9%, 148.6 MPa, 1588.6 MPa and 13.8 kJ kg(-1), respectively. The conductivity reached about 204.4 S cm(-1), more than 10 times larger than that of pre-compressed MWCNT blocks. After annealing at 1800 °C in vacuum, the graphitization improved remarkably. The pyrolytic carbon deposited on the surface of the MWCNTs was rearranged along the walls, and resulted in an increase of the number of walls of the MWCNTs.