The invention discloses boracic wear-resisting alloy steel and a preparation method thereof. The boracic wear-resisting alloy steel is prepared from, by mass percent, 0.20%-0.5% of C, 2%-6% of Cr, 0.4%-1.0% of Si, 3.0%-5.0% of Mn, 0.3%-2.5% of B, 0.2%-1.2% of Cu, 0.2%-0.6% of Ti, 0.05%-0.25% of Ca, 0.03%-0.3% of ReSiMg, 0.02%-0.18% of N, 0.05%-0.3% of Nb, 0.03%-0.08% of Al, 0.04%-0.13% of K, smaller than 0.03% of S, smaller than 0.04% of P and the balance Fe. Melting is carried out through an intermediate frequency furnace until the temperature ranges from 1,560 DEG C to 1,620 DEG C, ferrovanadium, ferrotitanium, potassium oxide, a silicon-calcium-barium alloy and nitrogen containing ferrochromium which are 60 meshes to 100 meshes, BC, BN, B2O3, Si3N4, Al and ReSiMg are matched according to the mass percent and then rolled into a metal cored wire with the diameter ranging from 8 mm to 15 mm through low-carbon steel with the thickness ranging from 0.12 mm to 0.25 mm, the metal cored wire is added into smelted molten steel as a boron supplying agent for boron supplying and metamorphic inoculation treatment, and the casting temperature of the molten steel ranges from 1,400 DEG C to 1,450 DEG C; and a casting is subjected to heat preservation for 2-4 hours at the temperature ranging from 920 DEG C to 1,150 DEG C, and air cooling is carried out to room temperature. The boracic wear-resisting alloy steel is good in strength, hardness, toughness, heat fatigue resistance and wear resistance and low in production cost.