The invention relates to a preparation method for a Zr (zirconium)-Nb (niobium)-Cu (copper) system alloy. The preparation method includes the steps of forging, quenching, hot extrusion, primary annealing, primary cold rolling and annealing, secondary cold rolling and annealing, and tertiary cold rolling and annealing, wherein in the primary cold rolling and annealing process, a workpiece after the primary annealing is treated with primary cold rolling, and treated with annealing treatment within a temperature range of 500 to 550 DEG C after the deformation reaches 50 to 70 percent; in the secondary cold rolling and annealing process, the workpiece after the primary cold rolling and annealing is treated with secondary cold rolling, and is treated with annealing treatment within a temperature range of 500 to 550 DEG C after the deformation reaches 50 to 70 percent; in the tertiary cold rolling and annealing process, the workpiece after the secondary cold rolling and annealing is treated with tertiary cold rolling, and is treated with annealing treatment within a temperature range of 450 to 520 DEG C after the deformation reaches 50 to 70 percent. Second-phrase particles of the Zr-Nb-Cu system alloy prepared through the method are distributed in a fine and dispersed manner; the corrosion resistance of the alloy prepared through the method is over 25 percent higher than that of alloys prepared through the traditional technique.