Thermal batteries have been widely used for military use due to their high specific power density and long storage life. With the development of electronic devices miniaturization, smaller and thinner thermal batteries are being studied as potential power sources for some special applications. Thin film FeS2 cathodes prepared by rolling and coating are compared with the FeS2 pellets shaped by traditional pressing. The discharging capacities of FeS2 thin films(thickness=120 μm) are 821 mAh?g-1 and 528 mAh?g-1 respectively with different current densities of 100 mA?cm-2 and 1 A?cm-2. The results show that the FeS2 thin films have a 20%-30% higher capacity than the pellets manufactured by traditional pressing, and the resistance of thin film thermal battery is only 81 mΩ. In addition, compared with the traditional thermal battery, the discharge capacity of thermal battery piled by thin-films is increased by 153%, and the weight and volume are reduced greatly.