The invention relates to a method for preparing iron oxide red pigment by utilizing titanium white waste acid, which belongs to the technical field of pigment powder. The method comprises the following steps: firstly locally neutralizing waste acid by utilizing ammonium, adjusting the pH of the waste acid, hydrolyzing and precipitating metal impurities such as titanium, aluminum vanadium and chromium in the waste acid in a sulfate form, allowing ferrous to remain in a liquid phase, oxidizing the ferrous into ferric iron by virtue of the combined effect of the chlorine gas and hydrogen peroxide with high reduction performance, obtaining a pretreatment solution, then performing enzymolysis on an acid-containing fruit, mixing an enzymatic solution rich in organic carboxylic acid and the pretreatment solution, extracting a chelated-state ferric iron by virtue of an extracting agent, mixing microorganisms and an extraction phase, fermenting, degrading organic carboxylic acid by utilizing microorganisms, enabling the ferric iron to be exposed again, then precipitating the ferric iron by utilizing the sodium hydroxide, obtaining ferric hydroxide precipitates, and sintering at a high temperature, thus obtaining the iron oxide red pigments. According to the method, the waste acid is used as a raw material, so that the source is sufficient, the cost is low, the entire process flow is simple and easy in operation, and the application prospect is wide.