The invention provides a carbon nano material / 
metal nano material composite nano ink which comprises 
solvent, an additive, a carbon nano material and a 
metal nano material. The carbon nano material / 
metal nano material composite nano ink is characterized in that the 
solvent can comprise water, 
alcohol organic solvent (
ethanol(
alcohol), isopropanol, n-
butanol and the like), ester 
organic solvent (
ethyl acetate, 
butyl acetate, 
ethylene-propylene acetate and the like), 
benzene organic solvent (methylbenzene, dimethylbenzene and the like) and 
ketone organic 
solvent (
cyclohexanone, 
acetone, methylethylketone, 
butanone and the like); the additive comprises surfactant, pH value stabilizer, defoaming agent, diluter, reinforcer and the like; the carbon nano material comprises a single-layer 
carbon nanotube, a double-layer 
carbon nanotube, a multi-layer 
carbon nanotube and 
graphene; the metal (
copper, silver, gold, 
platinum, 
nickel and the like, also including an 
alloy nano material, an ITO metal composite nano material and the like) nano material further comprises a metal 
nanoparticle, a 
metal nanowire or a metal 
nanotube; the components of the nano ink must include one carbon nano component and one metal nano component, such as a single-layer carbon 
nanotube and 
copper nanowire composite ink, a double-layer carbon 
nanotube and silver 
nanowire composite ink, a single-layer carbon nanotube and 
silver nanoparticle composite ink or any other possible combination; the components can be regulated according to specific applications; and a composite nano conductive film can be formed on different bases through different electronic printing processes. The ink can be used in the printing of a flexible base material and can be conveniently prepared into a flexible conductive film.