The invention belongs to a multifunctional resin coloring modifier and a preparation method thereof. The multifunctional resin coloring modifier comprises, by weight, 10-35 parts of modified melamine urea formaldehyde resin, 1-10 parts of water soluble dye, 1-10 parts of dyeing assistants, 1-10 parts of fire retardants, and 50-80 parts of water. The modified melamine urea formaldehyde resin is prepared from, by weight, 30-50 parts of formaldehyde, 30-50 parts of melamine, 30-50 parts of methyl alcohol, 10-20 parts of urea, 10-20 parts of polymerization inhibitors, and 40-60 parts of water. According to the multifunctional resin coloring modifier and the preparation method thereof, dyeing and functional modifying of wood materials are integrated, the good modified characteristic of the dyed wood is achieved which the dye penetration, leveling property, color fastness, light resistance and the like are achieved. The multifunctional resin coloring modifier and the preparation method thereof have the advantages that operation is easy, implementation is easy, the production cost is low, a dyed material is large in density, high in strength, stable in dimension, resistant to abrasion, resistant to flame, uniform and rich in color, firm and durable, energy is saved in the production process, and environmental friendliness is achieved.