The invention relates to an automatic dip-coating surface treatment system for hard composite plastic rolled materials. A material roll passes a tensioning device after going out of an unwinding device. Under the action of a heating device, the material surface is heated to an initial plastifying period state. The material surface going out of the tensioning device is conveyed into a dip-coating adhesive groove by guide rollers. The wet material surface coated with a polyester adhesive solution is perpendicularly conveyed into a solvent thermal evaporation device via guide rollers. The bottom of the solvent thermal evaporation device communicates with a solvent recycling tower through a pipeline. A high-speed fan is mounted in the middle of the pipeline for pumping solvent waste gas evaporated from the solvent thermal evaporation device into the solvent recycling tower. After the solvent in the adhesive layer is evaporated by the solvent thermal evaporation device, the coated material surface enters a surface treatment device comprising a mirror roller and a silica gel roller, and during the transferring of the mirror roller and the silica gel roller, pressurization molding and primary cooling are carried out. The material surface treated by the surface treatment device is conveyed to a cooling device via guide rollers, and the material surface subjected to cooling molding enters a winding device to be wound into a large roll after passing an edge alignment tensioning device.