To find an excellent candidate cathode materials for decreasing the cathode voltage drops, forming good side-ledge and more longer cell lift time, various graphite content, such as 30%, 40%, 75% and 100% graphitic cathode blocks from deferent companies were tested for the 300 kA aluminum reduction cells bottom relining. The properties, such as cathode voltage drops, electric resistance were detected after the cell startup. The obtained data showed that the electrical resistance of the cathodes will increase with the decreasing of graphite content in the blocks except for the full graphitized cathode. Some semi-graphitic cathodes could attain a value of voltage drops under 300 mV, which suggested that this kind of cathode blocks might be the best one for saving energy and prolong the cell lift time.