The invention discloses a red mud/Yellow River sediment artificial fish reef and a preparation method thereof, and belongs to the field of comprehensive utilization of solid waste resources. Raw materials comprise 100-400 parts of red mud, 100-400 parts of Yellow River silt, 30-100 parts of mineral powder, 50-200 parts of shells, 15-25 parts of an exciting agent and 25-80 parts of mixing water. The preparation method comprises the following steps: firstly, adding water glass as an exciting agent into mixing water to prepare a uniformly dispersed water glass aqueous solution; secondly, adding an aqueous solution into the red mud, the yellow river sediment, the mineral powder and the shell mixture for stirring, and carrying out compression molding on the stirred yellow river sediment slurry casting mold; and finally, maintaining the sample in an air environment, and removing the mold. Compared with a common cement concrete artificial fish reef, the preparation and production cost of the artificial fish reef is effectively reduced, meanwhile, the artificial fish reef has good strength and durability, and the alkalinity of the system is low. Comprehensive utilization of solid waste resources is promoted, the production cost of the artificial fish reef is reduced, other properties such as durability of the artificial fish reef are improved, and the artificial fish reef has remarkable environment-friendly, economic and engineering utilization values.