The invention discloses an electrostatic self-assembly three-dimensional flower-like cobalt disulfide/MXene composite material and a preparation method and application thereof. The composite materialis prepared by the following steps: stirring a soluble cobalt salt aqueous solution and a vulcanizing agent aqueous solution to obtain a mixed solution, carrying out hydrothermal reaction on the mixedsolution at 150-280 DEG C, performing cooling along with a furnace, carrying out suction filtration, and carrying out drying to obtain a solid A; adding the solid A into a polydiallyldimethylammoniumchloride solution, performing stirring, and performing washing to obtain a solid B; putting the solid B into an MXene aqueous solution, performing stirring, performing standing, carrying out centrifugal washing, and carrying out freeze drying to obtain a solid C; and under the protection of nitrogen, calcining the solid C at 500-700 DEG C to obtain the composite material. The composite material is self-assembled on an MXene nanosheet substrate through electrostatic interaction, the substrate can effectively accommodate the volume effect of cobalt disulfide in the charging and discharging process, and the composite material has excellent charging and discharging cycle performances, rate capability and high initial coulombic efficiency.