Multifunctional steel structure is a flexible all-purpose prefab steel building designed for mixed-use and comprehensive scenarios. It integrates the advantages of expandable space, combinable structure and multi-scene compatibility, and can be freely converted and partitioned for integrated use of office, reception, storage, light production and public service. The overall design is concise and versatile, easy to add floors, extend areas and modify internal layouts according to later demands. It features good ventilation, daylighting and thermal insulation performance, strong adaptability to different landforms and environment, eco-friendly construction and low later maintenance cost, serving as a cost-effective all-in-one building solution for multiple application needs.