As there exists the serious problem of environmental pollution caused by antibiotics at present, the experimental research on the adsorption of montmorillonite (Mt), a highly active clay mineral, for tetracycline (TC) from aqueous solutions was carried out in this paper. Batch adsorption experimental methods were used to make the investigation with the emphasis placed on the influences of initial TC concentration, initial pH as well as cation types of electrolytes and their concentrations on the adsorption properties of Mt for TC. The results show that the adsorption behavior of Mt for TC can be well described with Freundlich isotherm, and the maximum adsorption capacity calculated by the Langmuir equation was 625 mg/g; however, the strongest adsorption of TC on Mt may occur under the condition of higher acidic medium pHs (pH=2～4), followed by weak acidic-weak basic pHs from 5 to 9. In addition, varying types of cations can obviously affect the adsorption capabilities of Mt, suggesting that the higher their state of valence, the more evident the impact extent of TC adsorption. Mt is therefore a highly efficient adsorbent and can be applied to the treatment process of TC wastewater.