Abstract: In this research,the purpose was to screen out the best formulation of isopropyl myristate( IPM).Firstly,surfactants,co-surfactants,the quality ratio of them( Km) and hydrophilic lipophilic balance( HLB) values were determined by using the pseudo-ternary phase diagrams and the area of microemulsions( MEs) as the index.And the stability and configuration of MEs were measured by centrifugation and dyeing. The results showed that the stability of MEs was well when the IPM as the oil phase,Tweeen80 combined with Span80 as the composite surfactant,ethanol as the co-surfactant( IPM∶ Tweeen80 conbined with Span80∶ethanol = 4∶4∶2),Km = 2∶1 and HLB = 7.5.Under this condition,the maximum amount of water contained in the water-in-oil MEs was 15.3%.So it was possible and convenient for the pseudo-ternary phase diagrams to prepare MEs.