The effect of main alloying elements on thermal wear of cast hot-forging die steels was studied. The wear mechanism was discussed. The results show that alloying elements have significant influences on the thermal wear of cast hot-forging die steels. The wear rates decrease with an increase in chromium content from 3% to 4% and molybdenum content from 2% to 3%, respectively. With further increase of chromium and molybdenum contents, chromium slightly reduces the wear resistance and molybdenum severely deteriorates the wear resistance with high wear rate. Lower vanadium/carbon ratio (1.5-2.5) leads to a lower wear resistance with higher wear rate. With an increase in vanadium/carbon ratio, the wear resistance of the cast steel substantially increases. When vanadium/carbon ratio is 3, the wear rate reaches the lowest value. The predominant mechanism of thermal wear of cast hot-forging die steels are oxidation wear and fatigue delamination. The Fe_2O_3 and Fe_3O_4 or lumps of brittle wear debris are formed on the wear surface. The effect of main alloying elements on thermal wear of cast hot-forging die steels was studied. The results show that alloying elements have significant influences on the thermal wear of cast hot-forging die steels. with an increase in chromium and molybdenum content from 3% to 4% and molybdenum content from 2% to 3%, respectively Lower vanadium / carbon ratio (1.5-2.5) leads to a lower wear resistance with higher wear rate. With an increase in vanadium / carbon ratio, the wear resistance of the cast steel substantially increases. When vanadium / carbon ratio is 3, the wear rate reaches the lowest value. The predominant mechanism of thermal wear of cast hot-forging die steels are oxidation wear and fatigue delamination. The Fe_2O_3 and Fe_3O_4 or lumps of brittle wear debris are formed on the wear surface.