Construction method of fabricated steel trestle

The invention discloses a construction method of a fabricated steel trestle. The method comprises the following steps: completing the installation construction of a beret piece assembly frame with a preset length of a first span, installing an upper positioning frame on the upper surface of a preset position of the beret piece assembly frame, installing a lower positioning frame at a corresponding position of the lower surface of the beret piece assembly frame, and connecting the lower positioning frame with the upper positioning frame; inserting and driving the steel pipe piles by using the upper and lower positioning frames, sinking the lower positioning frame to the bottom and fixing, mounting a counterweight piece on the upper part of the lower positioning frame, and mounting a support frame between the adjacent steel pipe piles; cutting off steel pipe piles with preset sizes, mounting cap beams on each group of steel pipe piles in the length direction of the steel trestle, mounting carrying pole beams on