The invention discloses a small-block-shaped nickel-copper alloy preparation method based on a water washing technology. The small-block-shaped nickel-copper alloy preparation method based on the water washing technology specifically includes the following steps that the nickel copper matching ratio is calculated according to the nickel-copper alloy production requirement, then raw materials are weighed and taken, and are thrown into an intermediate frequency furnace in batches, the intermediate frequency furnace is powered on to melt materials, and after all the materials are molten, molten alloy is injected into a steel ladle; the steel ladle is moved to the position beside a cooling water pond, the molten alloy is poured into the cooling water pond, the pour-in speed is 100 kg/min, and the temperature of water in the cooling water pond is 70-100 DEG C; and after all the molten alloy in the steel ladle is poured into the cooling water pond, small-block-shaped nickel-copper alloy finished products can be obtained in a fish-up manner. The small-block-shaped nickel-copper alloy preparation method based on the water washing technology is used for preparing a small-block-shaped nickel-copper alloy, the block size is uniform, it is not needed to adopt molds in the production process, cost is low, the production period of the nickel-copper alloy is shortened, and the production efficiency and the product quality are improved.