Abstract: OBJECTIVE To prepare curcuma zedoaria oil-loaded submicron emulsion and investigate the effect of HLB on its physicochemical properties. METHODSThe high pressure homogenization method was employed to prepare curcuma zedoaria oil-loaded submicron emulsion. The particle distribution and zeta-potential were determined by using zetasizer. The stability of the submicron emulsion was investigated by centrifugalization. The solubilities of zedoaria oil in aqueous phase with various HLB value were determined. The dialysis method was established for determination of drug release behavior of curcuma zedoaria oil in the submicron emulsion. RESULTSCurcuma zedoaria oil-loaded submicron emulsion was charged negative and with the mean particle size between 123 nm and 154 nm. Solubilizations were observated obviously with emulsifiers of various HLB value, and solubilization multiples were between 5.5 and 8.2. In vitro drug release experiments indicated the drug release from submicron emulsion was lasted to 48 hours, and the release behavior was consistent with Higuchi equation. CONCLUSIONThe curcuma zedoaria oil-loaded submicron emulsions with various HLB value of emulsifier were prepared. Their physicochemical properties such as particle distribution and stability were different accompany with various HLB value of emulsifiers. Moreover, as HLB value of emulsifiers increased, more solubilizations were observated, and accelerated releases were observated when released in vitro, and was represented a sustained release.