The invention belongs to methods for removing silicon dioxide from low-grade bauxite, and in particular relates to a method for removing silicon dioxide from low-grade diasporite type bauxite. The method comprises the following steps of: mixing low-grade diasporite type bauxite with a sodium hydroxide solution containing a small quantity of stabilizing agent or with a sodium aluminate solution; dissolving out most active silicon dioxide in the low-grade diasporite type bauxite; and separating mixed slurry to prepare a high sodium aluminosilicate solution and a concentrate with a high silicate-to-aluminum (A/S) ratio. In the method, the grade of the bauxite is improved through quickly removing most silicon dioxide in raw material ores, thereby the problem of silicon scaling is effectively solved, and the use efficiency of equipment and the utilization ratio of bauxite resources are greatly improved.