A method for the determination of Al2O3 in bauxite, kaoline and clay minerals by EDTA-indirect titrimetry is proposed. The effect of different kinds of tartaric acids as masking agents on determination of Al2O3 was tested. From the experimental results, it suggested that the dextro-isomer and laevo-isomer tartaric acids can be used as masking agents instead of mesomeride tartaric acid and especially raceme tartaric acid. The analytical results of Al2O3 were satisfactory when seignette salt was used as masking agent. The method provides the advantages of more efficiency and simple operation.