The invention relates to a novel material with ultra-high thermal conductivity for a hot-stamping die. The steels in the market for the hot-stamping die are mainly various types of improved H13 and H11 high-alloy hot work die steels. The steel in the invention comprises the following compositions in percentage by mass: 0.150-0.35% of C, less than or equal to 0.25% of Si, 0.08-0.20% of Mn,1.0-2.0% of W,2.0-4.5% of Mo, less than or equal to 0.30% of Cr,less than or equal to 0.02% of V and the balance of Fe and inevitable impurity elements, wherein S in the impurity elements is less than or equal to 0.005%, P in the impurity elements is less than or equal to 0.01 and O in the impurity elements is less than or equal to 30 ppm (parts per million). The invention is characterized in that simple elements i.e. C, Mo and W are used as the main elements, and proper proportion of carbide is adopted; the contents of Mn and Cr are maintained low, and the content of Si is maintained ultra-low; the steel has superior machining property after being subjected to electro-smelting, electro-slag remelting, annealing, high-temperature homogenization, forging and annealing; through thermal treatment (1060-1100 DEG C quenching and high-temperature annealing), the toughness of the steel can reach the toughness of common hot-stamping die steel such as H13, and the hardness, annealing stability and the fatigue property of the steel are more superior; particularly, the steel with lower coefficient of thermal expansion and ultra-high thermal conductivity is more suitable for hot stamping.