Soybean protein isolate (SPI), gum Arabic (GA) and carrageenan (CA) were used as raw materials to prepare different polysaccharide and SPI complexes by physical mixture. The effects of different amounts (the mass ratios of SPI and GA/CA were 20, 15, 10 and 5) on the structure, properties and emulsion stability of protein-polysaccharide complexes were investigated. Finally, the interaction mechanism between protein and different polysaccharide complexes was confirmed. The structural characteristics of different complexes were analyzed by infrared spectrum, fluorescence spectrum and electron microscope. The physical and chemical properties of different complexes were determined by emulsifying property, particle size, Zeta-potential and surface hydrophobicity, and their stability properties were clarified by discussing the emulsifying activity, emulsifying stability, apparent viscosity and emulsifying index of different complex emulsions. The results showed that the two polysaccharides could form complexes with SPI under acidic conditions, and when the mass ratio of SPI to CA was 20, the highest Zeta-potential of the complex was (20.47±0.82)mV and the minimum average particle size was (1.37±0.01)μm, the emulsifying activity index was (106.46±4.75)m2/g, and the emulsifying stability index was (145.33±8.53)min, the stability of the composite emulsion was better under the condition. The addition of CA significantly reduced the endogenous fluorescence intensity of SPI and changed the secondary structure of SPI. SPI combined with CA to form a stable complex, which provided some theoretical support for the application of protein-polysaccharide composite emulsion in the transport of active substances.