The invention discloses a high-purity large-scale electroslag ingot and a production method thereof. The production method comprise the following procedures of molten iron desulphurization dephosphorization pretreatment, VD refining degassing, VD vacuum treatment, casting blank electroslag remelting and steel ingot hydrogen diffusion treatment. The electroslag ingot comprises chemical components with a low alloy content, and the cost is reduced; high-quality dephosphorization and deoxidation powder is selected and prepared, Ca-Si wire and Al wire feeding quantity and vacuum keeping time are controlled in the VD vacuum treatment procedure, electroslag is selected carefully for remelting a CaF2 slag system and an auxiliary material, hydrogen diffusion slow cooling heat treatment is adopted,four-term evaluation of smelting components of the obtained large-scale electroslag ingot reaches the grade less than or equal to 1.0, wherein the four-term evaluation comprises standard compliance, extremely high purity, compact internal structure and non-metal inclusion, the sum of alloy impurity elements of Sn + As + Sb + Bi + Pb is less than or equal to 0.015%, the ingot is a high-quality ingot type, and a novel process for producing the large-scale electroslag ingot is successfully initiated.