The invention belongs to the field of building construction and specifically relates to a novel steel box girder No. 0 block support and a No. 0 block support construction method. The novel steel boxgirder No. 0 block support comprises a steel upright mounted with a lateral bracing and a diagonal bracing; a main cross beam is mounted on the steel upright; a through track beam is mounted on the main cross beam; a limiting hanging lock sticking to the external side surface of a tower column lower cross beam is fixed under the bottom of the through track beam; and a limiting support sticking tothe external side surface of the tower column lower cross beam is fixed on the steel upright. During mounting, each sub block of a steel box girder is hoisted to a slide block of the through track beam, a traction system pulls the sub blocks to slide to designed positions one by one, the sub blocks are accurately adjusted by a jack to be supported on a temporary pier; and finally, each sub block is welded or bolted to form a whole No. 0 block. According to the scheme of the novel steel box girder No. 0 block support, the defect of weak anti-tipping capacity of a traditional support under the action of slip eccentric load is overcome, an embedded part and a buttress part do not need to be mounted on the top surface or the side surface of the tower column lower cross beam, and meanwhile, appearance defect problems such as internal rusting passage and concrete surface chromatic aberration of the tower column lower cross beam are prevented from being formed, the working efficiency is enhanced, and the safety and quality are guaranteed.