Co 9 S 8 @partly-graphitized carbon (Co 9 S 8 @C) composites with different carbon contents have been prepared by in-situ polymerization of polyaniline (PANI) and further calcination at 900 ℃. Cobalt species play catalytic role in the graphitization of PANI-based carbon, moreover catalytic effect is more obvious when the Co 9 S 8 content in Co 9 S 8 @C composites is higher. While the property and content of PANI-based carbon have important effect on the electrochemical performances of Co 9 S 8 @C composites. Co 9 S 8 @C composites with 27.6 wt% carbon content exhibit superior rate performance and cyclic stability as anode materials of lithium-ion batteries. Their specific capacities at 0.1, 0.2, 0.3 and 0.4 A·g −1 are 806, 749, 717 and 697 mAh·g −1 , respectively. Even at 1.0 and 2.0 A·g −1 , the specific capacities still preserve 652 and 601 mAh·g −1 , respectively. Moreover, their specific capacities retain 503 mAh·g −1 after 350 cycles at 1.0 A·g −1 . The good electrochemical performances of Co 9 S 8 @C composites with carbon content of 27.6 wt% should be ascribed to the appropriate content and partial graphitization of the carbon layer on the surface of Co 9 S 8 particles, which not only can effectively alleviate volume expansion of Co 9 S 8 particles, but also is beneficial for the rapid transmission of electrons and ions in the electrode reaction.