In order to explore the effect of high hydrostatic pressure on the functional properties of polysaccharide-protein mixture system. Using konjac glucomannan(KGM) and soybean protein isolate(SPI) as raw materials, the emulsifying activity, emulsifying stability, viscosity properties and microstructure of the composite sol were investigated after high hydrostatic pressure processing. The results showed that the functional properties were significantly improved when KGM-SPI composite sol was treated at 400 MPa pressure; And under 400 MPa treatment, the emulsifying activity and emulsifying stability achieved the best at 10 - 15 min(increased by 5.6 - 6.2% and 2.5 - 2.7% ),while the viscosity got the highest value at 15min (increased by 145.3%), compared to the control group. Moreover, the analysis of SEM showed that the composite sol presented a more uniform and dense three-dimensional network structure after 400 MPa treatment, and the interaction between them was enhanced.