The invention discloses a gluing mechanism of a sandpaper compound machine. The gluing mechanism comprises a rack, an upper air cylinder, a lower air cylinder, an upper silica gel roller connected with the upper air cylinder, a lower silica gel roller connected with the lower air cylinder, a gluing roller arranged between the upper silica gel roller and the lower silica gel roller, an oiliness glue scraper, a water-based glue scraper, and a water tank arranged on the lower end of the water-based glue scraper, wherein the upper air cylinder and the lower air cylinder are arranged on the rack; and the oiliness glue scraper and the water-based glue scraper are arranged on two sides of the upper glue roller. The gluing mechanism of the sandpaper compound machine, provided by the invention, has the advantages that both oiliness glue and water-based glue can be coated by one machine, thus being complete in functions, being capable of meeting the different gluing requirements of customers, and reducing the use cost.