Abstract: Surface modification process of aluminum hydroxide by wet method with the surfactants of Span was studied. Meanwhile，the surface modification effect was analyzed by the means of the water contact angle test，IR，particle size distribution，TG-DSC and so on.Results showed that the conditions，such as amount of modifier，modifying temperature，and modifying time，had a significant influence on the modification effect of aluminum hydroxide，and there were differences between the surfactants of Span and the corresponding optimum conditions，especially S-60 which as the modifying agent，could been got the best modifying effect of aluminum hydroxide under the conditions as follow：amount of 0.03（the mass ratio of modifier to aluminum hydroxide），reaction temperature of 85 ℃，and reaction time of 60 min.By modifying，aluminum hydroxide particle size distribution became more uniform，the surface wettability of the particles changed from hydrophilic to lipophilic.The surface modification of aluminum hydroxide by the surfactants of Span was mainly achieved through physical adsorption，so the chemical structure of aluminum hydroxide has not been changed，and the thermal stability was not significantly affected.

Key words: aluminum hydroxide, Span, surfactant, surface modification