The invention relates to an MnS@CoMn-LDH composite material, and a preparation method and an application thereof. The preparation method of the composite material comprises the steps of 1) dissolvingsoluble manganese salt in water, then adding sulfide, carrying out a primary hydrothermal reaction, and carrying out centrifuging, washing and drying to obtain MnS; and 2) dissolving the soluble manganese salt, soluble cobalt salt, ammonium fluoride and urea in the water, then adding the MnS, carrying out a secondary hydrothermal reaction, and carrying out cooling, centrifuging, washing and dryingto obtain the MnS@CoMn-LDH composite material. The composite material is prepared into a working electrode for a supercapacitor. Compared with the prior art, the MnS@CoMn-LDH composite material is synthesized through the two-step hydrothermal reactions; the composite material contains rich mesopores and micropores so as to achieve good electrochemical performance; the preparation method of the composite material is simple and environment-friendly; the synthesis time is greatly shortened; and the large-scale production of high-purity MnS@CoMn-LDH composite materials is facilitated.