Abstract: In order to improve the entrapment efficiency of natural plant essential oil,sodium alginate and porous starch were used as wall materials,and oregano essential oil was used as core material to prepare sodium alginate / porous starch oregano essential oil microcapsules with the sharp hole method.Single factor test and orthogonal test were adopted to optimize the preparation process and the structure of essential oil microcapsules were characterized by scanning electron microscopy.The results showed that the optimum process of essential oil microcapsules preparation was 1 ∶ 3 of the essential oil and starch ratio,2.5% of the sodium alginate solution concentration,1.5% of the calcium chloride solution concentration and 9# needle,and the embedding rate reached88.25%,yield was 44.27% and particle size was 915 μm.Scanning electron microscope images showed that the microcapsules prepared with porous starch and sodium alginate as wall materials had good appearance,the surface presented cross- linked porous structure,which made up for the appearance defects as single wall material of sodium alginate microcapsules in a certain extent.