Abstract: A dustproof structure of a grinding tool holder, which comprises a shaft portion and a counterweight portion connected to one end of the shaft portion. The counterweight portion comprises an eccentric block connected to the shaft portion, at least one bearing mounted in the eccentric block, a dustproof ring, and a grinding member assembling head assembled with the bearing. The eccentric block is formed with an assembly port for disposing the bearing and the dustproof ring, the dustproof ring is located on a side of the bearing facing the grinding member assembling head, and formed with a first continuous concave-convex structure on a side away from the bearing, the grinding member assembling head is formed with a second continuous concave-convex structure on a side facing the dustproof ring, the first and second continuous concave-convex structures match with each other and define dust blocking dots.