To address the issue of excessive DS-type inclusions in 1.2343 hot-work die steel produced by electroslag remelting （ESR）， a process approach involving slag system optimization was proposed. Two new slag systems （E40F and E50F） were evaluated in industrial trials. Using FactSage software and empirical formulas， key physical properties of the slag systems—such as basicity， viscosity， conductivity， and activity of certain components—were calculated， forming the basis for the ESR process. Industrial trials revealed that the E50F slag system exhibited the best overall performance， with moderate SiO₂ content enabling the modification of hard Al₂O₃ inclusions into low-risk spherical inclusions. It also combined moderate fluidity with Al₂O₃ inclusion suppression capability， making it the preferred choice for inclusion control in the finished product in production. The E40F slag system exhibited strong modification capability but suffered from high viscosity， leading to difficulties in inclusion flotation and higher residual inclusion levels， resulting in inferior performance compared to E50F. The 37 slag system exhibited the highest Al₂O₃ activity， causing significant secondary hard inclusion precipitation without modification capability， yielding the poorest inclusion control performance. Using the optimized E50F pre-melted slag significantly decreased the DS inclusions in 1.2343 hot-work die steel， achieving a rating level of 0.5 with all inclusions smaller than 15 μm. The total inclusion count decreased by 27% compared to the original slag system. The E50F slag system is more effective in removing inclusions from 1.2343 hot-work die steel.