Abstract: The carbonized cobalt disulfide (CoS2) powders were prepared by high-temperature roasting of the mixture of hydrothermal synthesized CoS2 and a certain amount of glucose. The microscopic structures properties of CoS2 before and after carbonization were studied by X-ray diffraction, scanning electron microscopy and laser particle size distribution instrument. The thin-film anode of CoS2 was prepared by the screen printing technology, and then the anode was assembled into LiSi/CoS2 single cells for the discharge performance test. The results show that a carbon layer was formed on the surface of the carbonized CoS2 particles, which cut off the effects of impurities formed in the CoS2 synthesis process on the performance of thermal batteries. Comparing to those of the un-carbonized CoS2, the initial discharge voltage spike of LiSi/CoS2 system thermal battery with carbonized CoS2 was reduced by 81.3%, and the effective specific capacity increased by 26%.