The present disclosure discloses a method and device for removing iron in an iron-containing solution in hydrometallurgy. This method comprises the steps of: adding an iron-containing solution in hydrometallurgy into a reactor through a first homogenizing distributor, controlling concentration of the ferric iron in the reactor below 1 g/L, controlling pH of the solution in the reactor to be 2.5˜4, the temperature to be 65˜100° C., and the reaction duration to be 1˜3 hours, performing solid-liquid separation for the solution after reaction, and removing the iron in the iron-containing solution in hydrometallurgy in the form of goethite.