Abstract: In order to recover rare earth efficiently from waste polishing powder, it is necessary to remove the silicon and aluminum impurities firstly. The removal of these impurities from the waste polishing powder by NaOH solution was investigated. The effects of alkali ratio (mass ratio of alkali to waste polishing powder), leaching time, leaching temperature and NaOH concentration were studied. As the results illustrate, alkali ratio and leaching time exert greater effects on the removal rate of silicon and aluminum impurities. When the waste polishing powder was leached under the conditions of alkali ratio of 1.0, 90 min, 90 ℃ and NaOH solution concentration of 1.00 mol/L, the leaching efficiency of silicon and aluminum was as high as about 95.37% and 97.93%, respectively.