The invention discloses a cooper-aluminum composite and a preparation method and belongs to the technical field of metal processing. The cooper-aluminum composite adopts electric arc spraying, wherein the spray voltage is 30-35 V; the spray distance is 100-150 mm; the wire feed rate is 3-4 m/min; the electric current is 120-150 A; the pressure of compressed gas is 0.65-0.75 MPa; and the compressed gas flow is 1.6-2.0 m<3>/min. Cooper is sprayed on the surface of an aluminum alloy matrix in the protective atmosphere of inert gases to form a cooper coating; the cooper coating sprayed on the surface of the aluminum alloy matrix cannot be oxidized, is uniform and compact, red purple in color and high in the bonding strength with the matrix; and the cooper-aluminum composite has good electrical conductivity and can be used to prepare high-voltage electrical products. By adopting electric arc spraying for the spraying of the cooper coating, the preparation method of the cooper-aluminum composite causes no pollution to the environment, is simple and convenient to operate, and is quick, time-saving and cost-saving compared with the traditional electroplating and chemical plating methods.