In this work, Pleurotus eryngii protein-polysaccharide conjugates (PE-PPCs) were used as the only stabilizer for the preparation of high internal phase emulsions (HIPEs). PE-PPCs presented spherical particles in solution, and their three-phase contact angle had a strong correlation with pH values, and the angle at pH 10.0 was almost 90°, showing the most balanced hydrophilicity and hydrophobicity. Subsequent tests had also confirmed that the emulsion prepared under this pH condition had the best performance. As expected, droplet size, apparent viscosity, and viscoelasticity of HIPEs stabilized by PE-PPCs were related to varying degrees with pH values, PE-PPC concentrations (c), and oil phase volume fraction (φ). Finally, the optimal conditions (pH 10.0, PE-PPCs concentration of 30 mg/mL, φ = 0.77) were obtained. Our findings in this study can be helpful for the preparation of food-grade HIPEs, and also have reference value in the field of studying the stability of protein-polysaccharide conjugates at the oil-water interface.