Enzymatic soybean protein and phospholipids as the main materials， building a sports nutrition food system， through conductance， potential， particle size， SDS-PAGE electrophoresis， ISO-DALT two-dimensional electrophoresis and microscopic observation， the droplet characteristics of aggregates and their composite emulsions and protein subunit changes were systematically studied. The results showed that pepsin could only degrade soybean protein to a limited extent， and the protein subunits were not changed significantly after enzymatic hydrolysis for 30 minutes； when enzymatic hydrolysis of soybean protein (enzymatic hydrolysis for 30 minutes) and phospholipid with the mass ratio of 5∶1， their aggregates had better droplet characteristics (P<0.05)； when the aggregates were prepared with this ratio as the wall material， it was found that the oil phase and water phase ratio of 1∶3 can be formed the more ideal oil-in-water emulsification system (P<0.05)； Compared with the enzymatic soybean protein emulsion， the composite emulsion droplets had a higher average particle size and potential (P<0.05). In the process of in vitro gastric digestion， the droplet characteristics (conductivity， potential and average particle size) of the composite emulsion were significantly higher than that of the enzymatic protein emulsion(P<0.05)， and the protein degradation rate was greater than that of the enzymatic protein emulsion， and all subunits except β subunit could be degraded. Therefore， it was deduced that there was a droplet “self-assembly” process in the in vitro gastric digestion of the composite emulsion， which will help the expansion of application in sports nutrition food for the soybean protein-food-emulsification system， and provide certain theoretical support for clarifying the mechanism of its digestion and absorption.