Ultra-thin fireproof coating has been developed in the direction of ultra-thin, super weathering performance and good decorative performance. Ultra-thin fireproof coating refers to the steel structure fireproof coating with the coating thickness of not more than 3mm, indoor ultra-thin fireproof coating NCB (BT-01) expands and foams when it is subjected to fire to form a dense fireproof and heat-insulating layer, which prevents the flame from expanding to the surface layer of the material, prevents the combustion process from proceeding, and reduces the loss caused by fire. Ultra-thin fireproof coating NCB (BT-01) can be sprayed, brushed or rolled. Compared with thick steel structure fireproof coating NH (BT-03) and thin steel structure fireproof coating NB (BT-02), ultra-thin fireproof coating viscosity is still fine, the coating is still thin, construction is convenient, and the decorative property is good. Ultra-thin fireproof coating can meet the requirements of fireproofing and decorative requirements at the same time. For the exposed steel structure, ultra-thin fireproof coating is the steel structure fireproof coating which is highly favored by users.