The invention belongs to the technical field of electroslag remelting and relates to an improvement of a process for industrially producing Inconel 690 (I-690) alloy electroslag remelting ingots, in particular to a process for industrially producing an ultrapure low-segregation I-690 alloy electroslag remelting ingot of 3 tons. An electrode bar smelted by a vacuum induction furnace is phi430mm in dimension, and a crystallizer is phi503/phi527mm*2400mm in dimension. Remelting process parameters are shown as follows: according to the requirements of I-690 alloy components, a five-component premelting slag system with a new proportion is adopted by the remelting, wherein the five-component premelting slag system comprises the five components: calcium fluoride, calcium oxide, aluminum oxide, magnesium oxide and titanium dioxide, and the total content of unstable oxide impurities, such as manganese oxide, ferrous oxide and silicon oxide, is less than 0.5 percent. Before the remelting is performed, an electrode is used after being baked at 700 DEG C for 8 hours, a slag charge is used after being baked at 680 DEG C for 8 hours, and argon shield is adopted during a remelting process. According to the process, the oxygen content of I-690 alloy after the remelting is performed can be reduced to 20 parts per million (ppm) or below, and thus, the goal of no oxygenation or less oxygenation is achieved after the remelting is performed. Moreover, sulfur content is reduced to 5ppm or below; the oxide inclusion grade is lower than 1, and the alloy after the remelting is performed is even in structure component, and therefore, the high-quality remelting alloy is obtained.