Abstract: The effect of sodium polyacrylate(PAAS)on the grinding efficiency of bauxite was studied and its mechanisms were also analyzed.The results showed that，compared with no grinding aids added，the content of -0.074 mm in the ground product was increased by 5.45 percentage points under the optimal grinding conditions adding PAAS as grinding aid when the amount of PAAS was 0.7%wt of bauxite.Because the physical adsorption and chemical adsorption were occurred on the bauxite surface，which could reduce the pulp viscosity，change the surface electric potential of the bauxite，enhance the surface appearance of particles and lower the surface hardness of the bauxite，the grinding efficiency of bauxite was increased by PAAS.

Key words: Bauxite, Grinding aid, Grinding efficiency, Mechanism