This utility model provides a cardboard laminating device, relating to the field of cardboardprocessing technology. The cardboard laminating device includes two sets of conveying mechanisms, a base plate disposed at the bottom of the two sets of conveying mechanisms, and a laminating mechanism disposed at the top of the base plate and between the two sets of conveying mechanisms. The laminating mechanism includes an upper laminating unit and a lower laminating unit. The upper laminating unit includes a pair of upper mounting plates, with an upper laminating roller and an upper film cylinder rotatably connected between the pair of upper mounting plates. The lower laminating unit includes a pair of lower mounting plates, with a lower laminating roller and a lower film cylinder rotatably connected between the pair of lower mounting plates. The upper and lower laminating rollers are arranged opposite to each other. A height adjustment mechanism is provided between the upper and lower mounting plates on the same side along the direction of movement of the conveying mechanisms. This laminating device can perform double-sided lamination on cardboard and can adapt to laminating boards of different thicknesses, with low processing costs and high processing efficiency.