The invention discloses a high-boron surfacing flux-cored wire with a two-phase compound reinforced main wear-resisting phase and an application method of the high-boron surfacing flux-cored wire. Theflux-cored wire adopts a H08A cold-rolled thin steel strip as an outer-layer wrapper, the wrapper is internally matched with high-carbon ferrochromium, ferro-boron, boron carbide, ferromolybdenum, ferromanganese, flake graphite, ferrosilicon and reducing iron powder to form a powder core, and the powder core is subjected to self-protective open-arc surfacing to form a surfacing alloy with the two-phase compound reinforced main wear-resisting phase. The components of the flux-cored wire are optimized, and are matched with a main wear-resisting phase multi-element alloying toughening way, and acoordinated regulation method on surfacing parameters such as voltage, current and welding speed is applied, so that heat dissipation flow which tends to be perpendicular to the surface of a molten pool is formed, and therefore, the main water-resisting phase which is composed of a (Fe, Cr, Mn)2B inner-core phase and an external (Fe, Cr, Mn, Mo)23(C, B)6 coating phase is in directional distribution. The high-boron flux-cored wire surfacing alloy has excellent abrasive wear resistance as a result of the main wear-resisting phase with 85% or higher of volume fraction, and can be used for a surfacing wear-resisting alloy layer on the inner wall of a sand-blast steel tube.