Most of the bauxite resources in China are kaolinite-diaspore bauxite of middle to low grade, with a fine dissemination, and are difficultly separated. Direct flotation de-silication has been shown to be an effective method for de-silication of diaspore. In this study the effect of different factors, including pulp temperature, density, pH value, depressant, and collector dosage, on direct flotation of diaspore were investigated by laboratory experiments. The optimum conditions were identified and the flotation performance was improved. The results show that under optimum conditions (a pulp temperature around 40 °C, a pulp density from 30% to 33%, a pH value from 9.0 to 10.0, an air flow rate of 0.5 m3/(m2 min), a dispersant level from 35 to 70 g/t, and a collector level around 1000 g/t) an Al/Si ratio of 6.97 is obtained starting from an initial Al/Si ratio of about 4.71. The recovery of Al2O3 under these conditions was 86.94%. Most of the bauxite resources in China are kaolinite-diaspore bauxite of middle to low grade, with a fine dissemination, and are difficultly separated. Direct flotation de-silication has been shown to be an effective method for de-silication of diaspore. study the effect of different factors, including pulp temperature, density, pH value, depressant, and collector dosage, on direct flotation of diaspore were investigated by laboratory experiments. The results show that the flotation performance was improved. optimum conditions (a pulp temperature around 40 ° C, a pulp density from 30% to 33%, a pH value from 9.0 to 10.0, an air flow rate of 0.5 m3 / (m2 min), a dispersant level from 35 to 70 g / t, and a collector level around 1000 g / t) an Al / Si ratio of 6.97 is obtained starting from an initial Al / Si ratio of about 4.71. The recovery of Al2O3 under these conditions was 86.94%.