Abstract: Coil terminal box(CTB) is the important constituent of the International Thermal-Nuclear Experimental Reactor superconducting magnet system. The heat leak of its components is frequently the main heat load source of the superconducting magnet which decides consume of liquid helium of the cryogenic system. Designs of thermal shield, superconducting busbar, current leads, valves and cooling pipes, and outer box of CTB are detailed described from reducing heat load point of view. They provide the theoretical base for the final structure design.