To satisfy the service conditions of TISCO 4 350 m3 blast furnace and the requirements to taphole clay, the study on the taphole clay for large blast furnace was carried out. The taphole clay with good workability, opening ability and high temperature performance was prepared by optimizing raw materials, grain size distribution, binder selection, etc. The trail application in TISCO 4 350 m3 blast furnace showed that the newly developed taphole clay had a satisfactory performance.