Tetracycline (TC) is a widely used antibiotic. Ferrihydrite and goethite are representative of amorphous and crystalline iron oxide minerals (IOMs). In this paper, the mechanisms underlying the interactions between TC and two typical IOMs were delineated. Both IOMs had specific adsorption, and formed stable inner sphere complexation. Electrostatic adsorption occurred during interactions between TC and the two IOMs, but only significantly influenced TC adsorption on goethite. Fe2+ was produced in solution after the interaction between ferrihydrite and TC, indicating a chemical reaction occurred. However, this phenomenon was not found in goethite interaction system. Na+ and Ca2+ had no significant effect on the amount of TC adsorbed on the IOMs. However, in the presence of Cu2+, TC adsorption on ferrihydrite and goethite decreased and increased, respectively. This is because the size of the Cu-TC complex becomes larger, which makes it difficult to be trapped in ferrihydrite pores. These results provide evidence how IOMs affect the mobility of TC.