The present invention relates to a construction method of superlong cable beam-free sections of a cable-stayed bridge. The first stage refers to the construction of five middle beam sections: the bracket+floating crane installation method is adopted, that is, the five cable beam-free sections in the middle of a tower area are sequentially hoisted up and placed on a lower beam bracket by using a floating crane, and tower beam temporary restraints are installed after the beams are connected into a whole. The second stage refers to the construction of two beam sections at the two ends: the platform+deck crane installation method is adopted, that is, the beam sections at each end are connected together on the backfield in advance and then stored on cofferdam top platforms on the both sides of a main tower, a deck crane above lifts and installs the beam sections, the lifting of the deck crane is conducted by using a midspan-and-then-sidespan asymmetry method, and the counterweight is increased or decreased in the construction process to decrease the unbalanced bending moment in the construction process. The construction method has unique advantages in terms of construction economy, construction cycle and construction safety, and the purpose of not applying floor steel pipe piles is realized.