The invention relates to the technical field of bridge construction, and discloses a system for lifting and sliding a large-tonnage steel box girder in a land area and a shoal area and a construction method thereof. The method comprises the following steps of: 1, arranging a lifting system beside a pier adjacent to a waterway, and arranging a sliding system below the lifting system and on a land side; 2, conveying a steel box girder section to a lifting position from the waterway, and lifting the steel box girder section by using a lifting device; 3, drawing a lifting transverse beam by using a jack and a steel stranded wire which are arranged on a lifting longitudinal beam to ensure that the lifting transverse beam, together with the lifting device and the steel box girder section, slides to a position above a sliding platform along the lifting longitudinal beam; 4, descending the steel box girder section to the sliding platform by using the lifting device; and 5, sliding the steel box girder section to a design position along a sliding track by using drawing equipment and arranging in position. The problem that a large floating crane is limited by the water level of a river channel and influenced by tide is solved, the construction period of a single steel box girder section is shortened, and work efficiency is improved; meanwhile, the steel box girder section can be arranged in the shoal area and the land area.