The invention relates to the technical field of bridge construction and specifically relates to a method for first-beam-later-pier construction of a pier top section of a cable-stayed bridge auxiliary pier. The auxiliary pier body is constructed for twice; the auxiliary pier body section is constructed at the first time; front pivot travelling basket waking space is preserved; and when a beam body on the auxiliary pier body section is poured, and the front pivot travelling basket passes the space on the auxiliary pier, the auxiliary pier top section will be constructed for the second time. The second construction of the auxiliary pier top section is characterized in that after the pier top section construction, the beam body on the pier top section will be anchored and locked on the pier top section; then, a pier top support is installed between the pier top section and the beam body; and after side-span folding, anchoring and locking of the beam body by the pier top section will be released. According to the invention, a support is installed easily with high installation efficiency; the elevation of the support can be adjusted accurately according to anchoring and locking relations, so that accuracy of support installation is increased; damage of pier body concrete is avoided; and stability of the whole bridge structure is enhanced.