In order to achieve the goal of high cleanliness of high-speed gear steel，especially the size of single-Particle D spherical inclusions ≤10 μm， electroslag process was developed to produce high-speed rail gear steel 18CrNiMo7-6 （/%：0.15-0.21C， ≤0.40Si，0.50-0.90Mn，1.50-1.80Cr，1.40-1.70Ni，0.25-0.35Mo，≤0.010P，≤0.010S），Φ250 mm steel billet production process is EBT electric furnace -LF-VD- casting 5.6 t electrode billet - electroslag remelting - forging - annealing - inspection. The electroslag slag system of 5.6 t electroslag ingot is CaF

2

∶Al

2

O

3

∶CaO∶MgO=65∶20∶10∶5 ， in the smelting process the melting rate is controlled at 500-550 kg/h，and the slag amount is 180-200 kg. Compared with the old slag system ，after adopting the new slag system the cleanliness of the produced high-speed gear steel is ［O］≤15×10

-6

， ［H］≤1.0×10

-6

，P≤0.008％，S≤0.005％，and non-metallic inclusion rating of A，B，C ，D and Ds series≤1.0 grade ， and the size of single-Particle D spherical inclusions is≤10 μm. Other hardenability and mechanical properties meet the requirements.