The invention relates to the technical field of grinding tools, in particular to a grinding tool formed by combination of a modified nano material and phenolic resin and a preparation method of the grinding tool. The grinding tool is composed of a grinding material, auxiliary filler and a modified binding agent. The modified binding agent comprises phenolic resin powder and modified nano additives. The grinding tool comprises, by weight, 3-30 parts of the grinding material, 5-60 parts of the auxiliary filler, 30-80 parts of the phenolic resin powder and 0.01-10 parts of the modified nano additives. As for the modified nano additives, a nano material undergoes surface lipophilic treatment and then undergoes in-situ polymerization to form the nano material wrapped with and modified by polymers. The prepared product has a good self-lubrication property, the wear durability of the grinding tool in the machining process is greatly improved, meanwhile, the grinding efficiency is not affected, the grinding material can be replaced, a formula and a process are optimized, the defect that a grinding tool in the industry cannot achieve high wear durability and high grinding efficiency at thesame time is thoroughly overcome, and great market prospects are achieved.