The invention relates to an inversely-proportional alkaline low-hydrogen type coating nickel-based welding rod ENiCrMo-3 and a preparation method of the inversely-proportional alkaline low-hydrogen type coating nickel-based welding rod ENiCrMo-3. Specifically, the inversely-proportional alkaline low-hydrogen type coating nickel-based welding rod ENiCrMo-3 is prepared in the manner that powder materials of following ingredients are evenly mixed, potassium sodium water glass accounting for 20%-25% of the total weight of the mixed powder materials is then added, evenly stirring is conducted, a nickel-based alloy welding core is coated with the mixture in a pressing manner, and then the inversely-proportional alkaline low-hydrogen type coating nickel-based welding rod ENiCrMo-3 is obtained through drying; and the ingredients of the inversely-proportional alkaline low-hydrogen type coating nickel-based welding rod ENiCrMo-3 comprise 15-30 parts of marble, 5-30 parts of fluorite, 5-20 parts of cryolite, quartz, titanium dioxide, rutile, mica, potassium titanate, feldspar, sodium alginate, sodium carbonate, silicon iron, ferrotitanium, electrolytic manganese, ferroniobium and chromium metal. According to the provided nickel-based alloy welding core, the number of the parts, by weight, of fluorides is over one time that of the marble. During welding, the inversely-proportional alkaline low-hydrogen type coating nickel-based welding rod ENiCrMo-3 is flexible and stable in electric arc blow force, less in splashing and good in deslagging effect, complete molten slag coverage is achieved, a formed weld joint is smooth, and the large-current resistance of the coating is good.