The invention discloses a dual-metal sliding bearing and a preparation method thereof. Carbon steel or stainless steel is taken as an outer layer material, and a powder metallurgy material taking a copper alloy as a basal body is taken as an inner layer material; the inner surface of the outer layer material is electroplated to form an electroplated copper layer with the thickness of 4-8 micrometres; the inner layer material comprises the following components by weight percent: 1%-20% of aluminum, 1%-8% of titanium, 1%-15% of stannum, 0.1%-5% of ferrum, 0.1%-2% of phosphorus, 0.1%-5% of nickel, at least one of 0.1%-2% of graphite and 0.1%-2% of molybdenum disulfide or 0.1%-2% of zinc stearate, and the balance of copper; and the bearing is impregnated with lubricating oil. The dual-metal sliding bearing has the advantages of low cost, high carrying capability, self-lubrication, excellent abrasion resisting capability, and the like, and can be widely applied to reciprocating swing positions of a swing arm, a bucket rod, a bucket, and the like of a large-tonnage and high-power excavator.