The invention belongs to the technical field of bearing brush materials, and discloses an aluminum-tin-copper alloy based bearing brush material and a preparation method thereof. The material takes in-situ TiB2 particles as an enhanced body, and takes an aluminum-tin-copper alloy as a matrix alloy, wherein volume percentage of the in-situ TiB2 particles is 4.0-12.0%. The preparation method comprises the following steps: (1) melting an aluminum ingot to obtain aluminum melt, and adding a reactant K2TiF6-KBF4 salt mixture and a reactive assistant Na3AlF6-MgCl2 salt mixture into the aluminum melt to obtain the aluminum melt containing in-situ TiB2 particles; (2) adding an aluminum-copper-zinc-manganese intermediate alloy and a tin block into the aluminum melt containing in-situ TiB2 particles to obtain an alloy melt; and (3) taking a NaCl-KCl-CaF2 gas mixture as a refining agent to refine the alloy melt, and casting the alloy melt into a casting mould, thereby obtaining the aluminum-tin-copper alloy based bearing brush material. The aluminum-tin-copper alloy based bearing brush material is excellent in comprehensive functional performance, is low in production cost, is environmentally-friendly, and is pollution-free.