Abstract: The purpose of the research is to optimize the process of preparing fish oil microcapsules by jet cavitation by using soy protein isolate as the wall material. The effect of wall material addition, emulsifier addition, core material addition and jet cavitation treatment time on emulsion stability and fish oil microcapsule embedding rate was studied by spray drying method. The response surface test was used to analyze various factors to obtain the most. The preparation process of the microcapsules was carried out, and the structure, physical and chemical properties and stability of the prepared microcapsule products were compared with those of the commercially available products. The feasibility of jet cavitation technology in the manufacturing process of microcapsules is discussed, which provides a preliminary theoretical basis for the application of jet cavitation technology in food. The results showed that the emulsion obtained under the conditions of 3.21% of wall material, 0.21% of emulsifier added, 19.70% of core material and 11.25 min of jet cavitation treatment time had better stability, and the embedding rate of fish oil microcapsules reached 94.14%; compared with commercially available fish oil microcapsules, the embedding rate increased by 4.91%. The microcapsule product has spherical microstructure, no cracks, pores and cracks, dense structure, fullness and fullness, and complete particle morphology, which basically achieves the intended purpose of embedding. The microcapsule product has a small particle size, a normal distribution and a narrow region. This indicates that the microcapsules have a uniform particle size distribution, and the particle size is small, the surface oil content is lowered, the embedding rate is increased, and the embedding effect is good. The angle of repose of the microcapsule powder was determined to be 40.39°, which was 9.37° lower than that of the commercially available microcapsules, and the smaller the angle of repose of the powder product, the smaller the frictional force and the better the fluidity. The microcapsule powder was measured to have a moisture content of 3.07% and a solubility of 96.30%, and the solubility was good. The results of differential scanning calorimetry show that the microcapsules have a high thermal dissolution temperature and can be used for storage at room temperature. This may be because the microcapsule particles in this study are spherical and dense in structure. The instantaneous high temperature during spray drying rapidly evaporates the water in the emulsion and hardens the surface. Therefore, the temperature and energy required for the phase transition of the sample are higher, and the thermal stability is better. The accelerated storage test of the fish oil after embedding showed that microencapsulation can improve the oxidative stability of fish oil. This is due to the dense and void-free structure of the microcapsule product in this study. The surface oil content is low, and the wall material is good for embedding fish oil, which hinders the influence of external conditions on fish oil and isolates oxygen, thus slowing down the oxidation rate, thermal stability can be better. Therefore, it can effectively delay the oxidative deterioration of fish oil microcapsules during storage and prolong the shelf life.