In order to study the purification method of octenyl succinate dextrin ester（OSDE） and its emulsifying properties，this study prepared OSDE with the aqueous phase method by using dextrin and octenyl succinic anhydride as the main raw materials.The product was purified by three methods including ethanol washing method，ion exchange method and membrane separation method.The results show that the purification effect of ion exchange method is the best and is friendly to subsequent determination of substitution degree；the purification effect of membrane separation method was the second；the ethanol washing method shows the worst purification effect.The morphology and group change of OSDE obtained by ion exchange method were analyzed.Scanning electron microscopy（SEM） shows that it is irregular lamellar，with sharp edges and corners，smooth surface，and slightly grooved or spotted corrosion areas；FT-IR analysis shows that the octenyl succinic acid group is successfully introduced into the maltodextrin molecule.After esterification modification，OSDEs viscosity-increasing ability is improved，and the shear thinning property，which is positively correlated with the degree of substitution，is wea-kened；the emulsion stability of the emulsion increases with increase of the degree of substitution of OSDE.Compared with the commonly used emulsifier gum arabic，the soybean oil emulsion of OSDE （DS0.0416） is slightly weaker in emulsification stability，but its rheological properties and microscopic morphology of the emulsion are similar to those of the commonly used emulsifier gum arabic but with lower cost.It shows that OSDE （DS0.0416） has a viable prospect as a substitute for expensive gum arabic in the application of emulsifiers and microcapsule wall materials.