The invention discloses a Ti core / shell structure 3 C 2 Alkene / Cu powder and its preparation method. Using electroless plating technology to Ti 3 C 2 Alkene is the carrier, and the surface is coated with a shell film composed of copper particles. The plating solution is mainly composed of copper sulfate pentahydrate, disodium edetate, and 2,2'-bipyridyl, the reducing agent is hydrazine hydrate, the reaction temperature is 45-95°C, and the pH is controlled at 9-13. The process is simple and low cost, and can obtain the core-shell structure Ti in a short time and stably. 3 C 2 / Cu powder, no pre-treatment such as roughening, sensitization, and activation of the substrate is required, and the thickness and particle size of the coating film can be adjusted, so core-shell nanocomposites with different properties can be prepared. This kind of core / shell powder has broad application prospects in catalysis, optics, electromagnetism and so on. This method is also applicable to MXene / metal powders with other core / shell structures (MXene includes M 2 Xene, M 3 x 2 ene and M 4 x 3 ene, etc.; shell metals include Cu, Ni, Sn, Co, etc.).