Abstract: The application properties，such as apparent viscosity，surface activity，degradation induced by enzyme or radiation，and emulsion stability of starch sodium octenyl succinate (SSOS) were studied in order to provide some guidance for its application. The results indicated that the apparent viscosity of SSOS increased with the rise of its degree of substitution (DS)，and the preparation methods of SSOS solution affected its apparent viscosity greatly，i.e. the solutions diluted from thicker ones had a higher apparent viscosity than those gelated directly to the specific concentration. The higher the DS of SSOS，the more notable the difference. The surface activity of SSOS was enhanced with the rise of its DS，i.e. a higher DS meant a lower surface tension of the solution. SSOS could be degraded by both enzymes and γ-rays，but the degradation regularities were different. The rate of degradation decreased with the rise of DS during enzymatic degradation while increased with the rise of DS during radiation degradation induced by γ-rays. Then the orthogonal experiment was designed for obtaining the optimal emulsification conditions. The results showed that SSOS had excellent emulsification property，and the optimized emulsification condition was DS 0.050，the ratio of oil-SSOS solution 0.10 mL/mL，SSOS concentration 0.05 g/mL，stirring speed 700 r/min，and the temperature，because of its slight influence on emulsification，could be selected as needed.