Abstract: The problem of wear and corrosion of the silver plating layer on the contact surface of the outdoor high-voltage isolating switch in the substation is prominent, which leads to serious heat of the contact, and brings great hidden dangers to the safe and stable operation of the power grid.The silver-graphite-graphene composite coating with excellent comprehensive properties was prepared by composite electrodeposition technology, in which potassium iodide was used as the coordination agent for silver electroplating in the cyanide-free system. The influence rules of different graphite additions on adhesion, contact resistance, corrosion resistance and surface morphologies were analyzed by various test and characterisation methods, such as binding force test, field emission scanning electron microscope (FESEM), transmission electron microscope (TEM), hydrophobicity test, contact resistance test and electrochemical corrosion test, etc. The results show that when the graphene content is 2 g·L^-1 and the graphite content is 30 g·L^-1, the coating has the dense structure, and is well bonded to the substrate. Me anwhile, the comprehensive properties of the silver-graphite-graphene composite coating are best, with the lowest roughness of 0.48 μm and moderate contact angle and contact resistance of 98.3° and 46.7 μΩ, respectively.