The invention discloses a rare-earth oxide doped tungsten-copper alloy composite material and a preparation method thereof. The rare-earth oxide doped tungsten-copper alloy composite material comprises, by mass, 14-39.9% of copper, 0.1-3.0% of rare-earth oxide and the balance tungsten and unavoidable impurities. The rare-earth oxide doped tungsten-copper alloy composite material is composed of tungsten, copper and rare-earth oxide. The rare-earth oxide is doped into the tungsten-copper alloy as a second phase, so that the sintering performance of the tungsten-copper alloy is remarkably improved. The tungsten and the copper are wrapped on the periphery of the rare-earth oxide to form a crystal developing completely, and the tungsten and copper elements have good wettability under the action of the rare-earth oxide. Molecule-level mixing of the tungsten and copper is achieved, the compactness of the tungsten-copper alloy is greatly improved, and the strength, rigidity and heat conduction and electricity conduction performance of the final tungsten-copper alloy are remarkably improved.