Metal powder type flux-cored wire and preparation and application thereof

The invention discloses a metal powder type flux-cored wire comprising a carbon steel skin and powders filled inside it. The powders comprise the following components and percent thereof accounting total weight of the flux-cored wire: TiO2 0.20 to 1.5%, SiO2 0.1-0.5%, any one of Na2O or K2O or mixture with optimal mixing ratio 0.1-0.50%, SiO 0.15-0.65%, Mg 0.08-0.45%, Mn 0.9-2.4%, Cr 0.15-1.0%, Ni 1.5-4.5%, Ti 0.15-0.45%, B 0.004-0.012% and any one of NaF or CaF2 or mixture with optimal mixing ratio 0.5-1.5%. When the flux-cored wire is being welded, slag quantity on the welding seam surface is small, the deposition efficiency is high, the sputtering is few, the flux-cored wire has good low temperature impact toughness and anticracking ability, and diffusible hydrogen reaches the super low hydrogen level.