The invention provides a method for improving emulsion stability by electrochemical soybean protein isolate. Soybean protein isolate is modified by a self-made electrochemical modified protein reaction kettle, a soybean protein solution is placed in a cathode electrolysis cell, and direct current with a certain current density is introduced for electrolysis; after the reaction is finished, samplesare taken out for vacuum freeze-drying to obtain electrochemically modified protein freeze-drying powder; the modified soybean protein isolate is dissolved in a phosphate buffer solution, rose seed oil is added into the solution, and homogenization treatment is carried out to prepare an emulsion. When the soybean protein isolate solution with the concentration of 0.050 g/L is treated by 4 mA/cm<2> direct current, electrochemical modification is carried out for 120 min, a spatial structure of the obtained soybean protein isolate is changed, the content of an alpha-helix structure is reduced, and the content of beta-folding and irregular curling is increased. The emulsion is prepared by homogenizing the electrolyzed soybean protein isolate solution with the rose seed oil, and has strong stability.