The invention discloses a high-toughness self-protecting flux-cored wire applicable to welding of a high-grade steel pipeline and belongs to the field of a welding material. The self-protecting flux-cored wire consists of a steel belt and flux core powder, and is characterized in that the welding wire comprises the following chemical deposited metal ingredients in percentage by mass: 0.01wt% to 0.08wt% of C, 0 to 0.5wt% of Si, 0.5wt% to 2.0wt% of Mn, smaller than or equal to 0.02wt% of P, smaller than or equal to 0.01wt% of S, 0.5wt% to 1.5wt% of Al, 3.0wt% to 4.5wt% of Ni, one or several of alloy elements including 0 to 0.08wt% of V, 0 to 0.5wt% of Co, 0 to 0.06wt% of Zr and 0 to 0.02wt% of rare-earth Ce, and the balance of Fe and inevitable impurities. The high-toughness self-protecting flux-cored wire has the advantages that generation of lots of smoke and harmful gases is prevented during a welding process of the flux-cored wire; the content of nitrogen and oxygen in a melting pool is relatively low; the content of free nitrogen in weld metal can be reduced below 150ppm; solidified tissues of a weld joint are thinned lath bainite tissues and particle-like bainite tissues; MA components are thinned and dispersed; the impact toughness of a self-protecting weld joint is effectively improved.