The invention relates to an exposed building steel structure, in particular to a field paint construction method for the exposed building steel structure. The steel structure of the filed paint construction method for the exposed building steel structure is pre-painted in the processing plant and is built by design by transporting to the site, comprising the set-up steps for painting the protection shed before construction, which the supporting system of the protection shed is formed on the full scaffold by using the steel bar, then the colorless, transparent and soft glass shed cloth is paved on the scaffold and the shed cloth is compressed and fixed by using the wood, and the painting patching steps including the foundation processing, the penniform processing of the original paint and the transition processing of the color of the repair paint and the original paint. Under the field paint construction method for the exposed building steel structure, the construction technology of the field paint to the exposed building steel structure is improved and the creativity of the architecture is more reflected by the appearance of the paint.