The invention discloses a construction method of a water trestle, and relates to the field of bridge construction. The method comprises the following steps: pre-setting a segment channel, horizontally arranging a movable platform on the top of the segment channel, and forming a first fixing hole, a second fixing hole, a first pile hole, a second pile hole, a third pile hole and a fourth pile hole in specified underwater installing points; adjusting the movable platform, adjusting a first back support leg and a second support leg, inserting a first front support leg into the first fixing hole, inserting a second front support leg into the second fixing hole, adjusting the first back support leg and the second back support leg, piling a ninth support pile into the first pile hole by using a piling device, piling a tenth support pile into the second pile hole, piling an eleventh support pile into the third pile hole, and piling a twelfth support pile into the fourth pile hole; grabbing a segment to be erected by using an overhead crane and placing the segment at a specified position. By adopting the construction method of the water trestle, the construction period can be shortened, the construction cost is reduced, and construction of a large-span water trestle is finished.