Comparative study on LiFePO4/C preparation process of adding carbon source in precursor and pre-sintered, marked as LFP-1(in-situ carbon coating) and LFP-2, respectively. The effects of carbon content, morphology, particle size and surface carbon structure on the electrochemical performance of LiFePO4/C cathodes were studied by means of C-S test, XRD, SEM, BET, Raman. SEM images show that particle size of the LFP-1 and LFP-2 are about 10μm and 100nm respectively. The EIS and galvnostatic charge-discharge tests indicate that the LFP-1 has lower charge transfer resistance Rct, better rate and cycle performance than that of LFP-2, which can be contributed to the different microstructure and the higher degree of graphitized carbon of LiFePO4/C. Raman spectroscopic analysis shows that the ratio of the ID/IG and Asp3/Asp2 of LFP-1 is lower that of LFP-2, which results in the higher degree of graphitized carbon of LFP-1. This result has important significance to improve the overall performance of olivine cathode materials for lithium ion batteries.