The invention discloses a copper-steel double-metal composite casting method for a plunger pump rotor and belongs to the technical field of double-metal casting. The method includes steps of machiningof a steel base body, pretreatment of the steel base body, performing of a heat treatment annealing technology on the steel base body, Ni-Cu-P multi-element nickel plating treatment of the inner surface of the steel base body, flux treatment, preheating of the steel base body, smelting of a lead tin bronze alloy, performing of a hot dipping technology, casting and machining, and the plunger pumprotor is prepared. The performance of the double-metal combined surface obtained in the casting manner reaches the standards, the equipment input is low, the technologies are simple and convenient tooperate, the workpiece cost is reduced, and the method is suitable for wide popularization and application and has the broad prospect. Compared with the powder metallurgy method, the method has the advantages as follows: the performance is more excellent, the heat treatment procedure is omitted, the time is saved, and the cost is reduced.