The invention provides a granular manganese dioxide/titanium carbide composite material and a preparation method thereof. The method includes: respectively dispersing Ti3C2 nanopowder and dopamine hydrochloride into ultrapure water, well mixing, and stirring under a shading condition; adding Tris- buffer solution, and continuing stirring under the shading condition; subjecting obtained mixed solution to separation, washing and drying to obtain Ti3C2@PDA nanopowder; adding the Ti3C2@PDA nanopowder into CTAB solution, uniformly dispersing, adding KMnO4 solution, and performing liquid phase reaction; naturally cooling after reaction to obtain the granular manganese dioxide/titanium carbide composite material. By adoption of the method, granular manganese dioxide in uniform distribution can beformed on the surface of titanium carbide, and the obtained composite material is great in electrochemical performance. The preparation method is low in equipment requirement, convenient and simple in operation, low in cost and beneficial to industrial large-scale production.