The invention discloses a welding electrode for welding -50 DEG C low-temperature pressure container steel. A core wire of the welding electrode is H08E of low S and P; a cover is prepared by the following components in parts by weight: 32-40 parts of marbles, 15-23 parts of fluorite, 4-8 parts of rutile, 5-7 parts of silica powder, 11-15 parts of iron powder, 5-9 parts of silicon iron, 3-6 parts of ferromanganese, 1-3 parts of ferrotitanium, 1.5-2.5 parts of metal nickel, 1-3 parts of phlogopite, 1-2 parts of sodium carbonate, and 0.5-1.0 part of graphite; all the components of the cover are evenly mixed, and 3.2 M pure sodium water glass of 24 weight% by the total weight of the components is added for mixing to prepare the cover; the rest production process of the welding electrode is performed by a conventional technology; the heat treatment is performed after the welding; and the temperature of 620 DEG C is keep for 1 hour, so that the mechanical performance is stable, the tensile strength reaches 560-620 Mpa at room temperature, and the -50 DEG C V-shaped gap impact power reaches above 110 J to satisfy the welding of the -50 DEG C low-temperature pressure container steel.