In this paper, carbon nanotubes (CNTs) are added in order to investigate their influence on the electronic conductivity of LiFePO4 cathode. CNTs/LiFePO4 composites are prepared by in-situ chemical vapor deposition method and the traditional mechanical mixture method respectively in order to investigate the influence of CNTs as an additive on the electrochemical performance of LiFePO4 cathode. The particle morphology and electrochemical performances of the CNTs/LiFePO4 composites are characterized and compared with commercial cathodes, LiFePO4 mixed with carbon black. The in-situ synthesized CNTs/LiFePO4 composite by chemical vapor deposition method maintains full retaining ratio after 100 cycles at 1C and 94.5% retention after 20 cycles at 10C, which precede the CNTs/LiFePO4 composite fabricated by the mechanical mixture method as well as the commercial cathode. The enhanced electrochemical performance is due to the excellent interface bonding between LiFePO4 and CNT in in-situ synthesized CNTs/LiFePO4 composites. The interface benefits the electronic conductivity of the composites, as well as the polarization reduction.