The invention belongs to the technical field of emulsion preparation, and discloses a stable-protein high-internal-phase oil-in-water emulsion and a preparation method thereof. The method comprises the following steps: a protein is dispersed into water, after the protein is fully hydrated, an aqueous phase protein solution is obtained, an oil phase is added, emulsification is performed, and therefore the stable-protein high-internal-phase oil-in-water emulsion is obtained. The method disclosed by the invention does not need any coagulants or surfactants, and the obtained high-internal-phase oil-in-water emulsion has good viscoelasticity, high heat stability and storage stability, and an excellent protection or controlled release effect on the oil phase; and the emulsion has good gelling performance, strong plasticity and remoldability, facilitates further processing, and has good application prospects in the fields of chemical products, daily chemicals, pharmaceuticals, food and healthcare products.