This paper describes the technical indexes of the graphitized cathode block(GCB)self-manufactured in China and the industrial experiments were carried on 300kA cells.The results show:the use of GCB can low the cathode voltage by 90mV,enhance the CE by 1.5% at least,and get back the increased overhauled cost when the cell has run for 900 days.So this material is the main developing direction for the large cell's lining.