The invention provides a vanadium disulfide nanosheet coated with oxo-vanadium hydroxide and a preparation method and application thereof. The preparation method comprises the following steps: dissolving sodium metavanadate and thioacetamide in deionized water in a magnetic stirring state simultaneously; then, pouring the solution into a reaction lining for sealing, loading the lining into an outer kettle for fixing, and placing the outer kettle into a homogeneous phase reaction instrument; lastly, cooling a reaction product, washing, collecting and drying to obtain the VOOH-coated VS2 nanosheet. The VOOH-coated VS2 nanosheet prepared by the method has uniform chemical composition, higher purity, uniform appearance and a specific self-assembly structure, and shows superior electrochemical performance when being taken as a sodium-ion battery electrode material. Moreover, by adopting the method, the defect of high temperature in a conventional calcining method is overcome, and large-sized equipment and severe reaction conditions are not needed; the vanadium disulfide nanosheet has the advantages of adoption of cheap and readily-available raw materials, low cost, high yield, no need of posttreatment and environmental friendliness, and can be suitable for large-scale production.