Abstract: Using AlCl₃·6H₂O as a raw material, polyaluminum (PAC) and polyaluminum tanning agent (PAT) were prepared by a slight alkali addition method. The Al_n(OH)_m structure of PAC was characterized experimentally. The solubility of PAT and the correlation between standing time and the particle size distribution in the suspension were measured. The stability of PAT solutions mixed with salt,vegetable extract and fat-resistant emulsion was investigated. The results show that the stability of the three solutions is related to the storage time. The application of PAT to the main tanning and retanning processes of leather indicated that the grain surface was fine, the thickness was increased significantly,the physical and mechanical properties were improved.