Under W/O emulsion method, alumina powder of which the starting material was aluminum nitrate (Al(NO₃)₃·9H₂O) was prepared by changing the type and composition of emulsifiers on the experimental conditions of 8:1.5 of O:W volumetric ratio, and of 11,000 rpm and 10 min. of agitation rate and time. Emulsifiers were sp80, as a main surfactant, tw80, as mixed surfactants with sp80, and n-butanol, as co-surfactant. As results, prevention against aggregation and coalescence phenomena among alumina particles were remarkably enhanced by using sp80 together with small amount of n-butanol as well as tw80. And also, particle size of alumina prepared with the above condition was much smaller than that prepared with on single surfactant of sp80.