The invention discloses a fully-automatic cover sucking and pasting system for a product box. The fully-automatic cover sucking and pasting system comprises a main beam (1), wherein the two sides of the main beam (1) are equipped with supporting plates (2); bearing bases (3) are arranged on the supporting plates (2); threaded shafts (4) are arranged on the bearing bases (3) in a penetrating mode;slide nuts (5) are in threaded fit to the threaded shafts (4); the two sides of the slide nuts (5) are equipped with nut side shafts (6); lifting rings (8) connected with lifting hooks (7) are rotatably connected on the nut side shafts (6); the end part of the main beam (1) is equipped with a lifting part (9); the lifting part (9) comprises end teeth (10) arranged on the end part of the main beam(1); the inner sides of the end teeth (10) are equipped with inner teeth (11); a clamping slot (12) is formed between the end teeth (10) and the inner teeth (11); one side of the clamping slot (12) ofthe inner teeth is provided with a vertical surface (13), and the lower part of the vertical surface (13) is equipped with an inclined surface (14), so that the clamping slot (12) is divided into anupper straight slot (15) and a lower inclined slot (16); and the lower parts of the inner teeth (11) are equipped with fastening bolts (17) which are inclined upwards.