Glycinin (11S) is a kind of high-quality plant proteins, while soyasaponin (Ssa) is one of natural amphiphilic small molecules. Both of them can be used as interface stabilizers to prepare oil-in-water emulsions, but the stability of these emulsions is poor under partial environmental factors. In this study, a mixture of 11S and Ssa was used as a stabilizer to prepare a composite emulsion, and the influence of typical environmental factors (pH, temperature, freeze-thaw) on the stability of 11S-Ssa composite emulsion was investigated. Multiple light scattering technology was employed to determine the overall stability of emulsions under different conditions of heat (90℃ and 120℃) and acidification (pH 2.0,3.0 and 4.5) treatments. The particle size distribution, particle size and flocculation rate of the composite emulsion after heat, acidification and freeze-thaw treatment were characterized. The results showed that acidification treatment significantly affected the stability of these emulsions. After heat treatment, the stability of the emulsions was reduced, but the stability of the composite emulsion with Ssa mass fraction of 0.05%-0.50% was still better than the emulsion stabilized by 11S alone. The stability of the emulsion was poor at pH 4.5, and a more serious stratification phenomenon appeared. After further lowering the pH to 2.0, the stability of the emulsion was improved, and the TSI value of emulsion in each group was reduced to 8.5 within 24h. In addition, adding a certain mass fraction of Ssa 0.05%-0.50% reduced the flocculation rate of freeze-thaw composite emulsion. This study showed that adding some soyasaponin could improve the stability of 11S emulsion under heat and acidified treatment, but did not significantly improve the emulsion instability after freeze-thaw treatment.