Soy lipophilic protein (LP) and hydroxypropyl methylcellulose (HPMC) can form an LP-HPMC complex spontaneously after being combined under neutral conditions (pH value 7.4), but there are still some selfassembled LP and HPMC presented in solution. At present, the research still can not achieve the maximum compounding degree of LP-HPMC and the target of the most binding sites. Fluorescence and infrared spectroscopy were used to study the effects of different ultrahigh pressure treatments on the degree of LP-HPMC compounding and the force. The effects of ultrahigh pressure on structureactivity relationship of structural changes and functional properties of LP-HPMC were analyzed by emulsion activity and emulsion stability measurement, surface hydrophobicity analysis and dynamic light scattering particle size analysis. The results showed that the LP-HPMC complex was bound by noncovalent interaction and the secondary structure of the protein was changed accordingly. When the pressure was 400MPa, the maximum solubility and minimum surface hydrophobic value of the composite were 41.1% and 57.832, respectively, and the emulsification activity and emulsion stability index were also the best.