The invention discloses a welding electrode and a coating for welding under a wading environment, and preparation methods of the welding electrode and the coating. The coating comprises the followingcomponent raw materials of, by weight, 35-50% of rutile, 10-20% of calcium carbonate, 5-15% of fluorite, 7-18% of mica, 2-9% of ferrosilicon, 3-9% of ferromanganese, 4-10% of titanium and 1.5-5% of yttrium. Potassium sodium water glass with the weight being 18-30% of the total weight of the coating is further added into the coating, and the mass ratio of potassium oxide to sodium oxide in the potassium sodium water glass is 2:1. Meanwhile, the invention further discloses the preparation methods of the welding electrode and the coating. The preparation process is simple, arcing is easy during welding, electric arc combustion is stable, the phenomena of arc quenching and breaking are avoided, an obtained welded seam is attractive in forming, the tensile strength of a butt-joint connector canreach 550 MPa, the thickness of the butt-joint connector is four times that of a plate, cracks are avoided when the cold bending angle is 180 degrees, the advantages of good welding manufacturability, convenient test operation, high welding efficiency and the like are achieved, and welding of workpieces under the wading environment can be met.