The invention discloses a water-coated transfer printing process for wood, plastic, and metal products, which comprises the following steps: according to the necessary background color, spraying oil paint on the surfaces of the wood, the plastic, and the metal products; spreading a water-coated transfer printing film on the water surface by putting the surface with printing ink patterns to face upwards; spraying an activator on the water-coated transfer printing film evenly through a spray gun when the water-coated transfer printing film is softened and spread levelly; and according to the positions of the patterns floating on the water surface, pressing an obtained product downwards into the water for 2 to 10 seconds and taking out the product, and transferring the patterns on the water-coated transfer printing film to the surface of the product under the action of water pressure. The process further comprises the following steps: washing the obtained product clean by water and then putting the product into a drying furnace to be dried at a temperature between 50 and 70 DEG C; or using a blowing gun to blow off the water, drying the product at room temperature, spraying a layer of transparent oil paint on the surface of the product, putting the product in the drying furnace and curing the product at a temperature between 50 and 160 DEG C. The compositions of the activator are as follows according to percentage by weight: 33 percent of xylene, 15 percent of butyl acetate, 15 percent of methyl acetate, 10 percent of methyl isobutyl ketone, 5 percent of isobutanol, 8 percent of isophorone, 5 percent of methyl methacrylate, 7 percent of cyclo ethyl ketone, and 2 percent of nitrocellulose resin.