Abstract: The purpose of this article was to investigate the effect of structure on the transdermal behavior of meloxicam microemulsion.Meloxicam microemulsions containing of oleic acid，Cremophor RH 40，ethanol and water(K_m=2) were prepared，and the structures of the microemulsion formulations along dilution line 91 in the microemulsion phase diagram were determined by electrical conductivity，viscosity and surface tension.Moreover，the formulation improvement in the solubilization of meloxicam and the transdermal permeation coefficient of the microemulsions were evaluated.It was proved that W/O type microemulsion had the best solubilization potential，followed by B.C.and O/W，and that O/W microemulsion had the best permeation rate，followed by B.C and W/O type.Thus the structures of microemulsion had accounted for the solubilization potential and transdermal permeation.