The invention discloses a method for preparing iron oxide red and recycling silver through ferroalumen residues. The method comprises the steps of leaching the ferroalumen residues through hot acid, removing impurities through leaching liquid, directly preparing iron oxide red through a hydrothermal method and extracting silver through hot-acid leaching residues. According to the step of leaching the ferroalumen residues through hot acid, leaching is carried out for 1-4 h at the temperature of 60-100 DEG C, and hot-acid leaching liquid and the hot-acid leaching residues are obtained. According to the step of removing impurities through the leaching liquid, iron powder replacement for copper removing is carried out, lead, cadmium and arsenic are removed through vulcanization, H2O2 oxidization is carried out, and purification liquid is obtained. According to the step of directly preparing iron oxide red through the hydrothermal method, an additive is added into the purification liquid, a reaction is carried out for 0.5-3 h at the temperature of 120-150 DEG C, and the product of iron oxide red is obtained. According to the step of extracting silver through the hot-acid leaching residues, silver leaching and silver-enriched liquid impurity removing are carried out, and a reaction is carried out for 2-4 h at the temperature of 40-100 DEG C in silver leaching. During preparing of iron oxide red, the iron settling rate is higher than 93%, the silver recycling rate is higher than 94%, and the purity of iron oxide red is higher than 97%. The method is simple in technical process and high in comprehensive metal recycling rate, and efficient recycling of iron and silver in the ferroalumen residues is achieved to the largest degree.