The invention relates to a light steel structural house with an outdoor corridor mudsill, which comprises a lower house structure and an upper house structure, and adopts the technical key points that a hollow metal section supporting layer is arranged between the lower house structure and the upper house structure, an outward extending part of a metal section in the supporting layer is the outdoor corridor mudsill, and auxiliaries for manufacturing an outdoor corridor are fixedly connected to the outdoor corridor mudsill in turn. When the outdoor corridor is installed, corridor upright postsare saved and the outdoor corridor forms an integral structure with the light steel house, so not only safety and stability are greatly improved, but also occupied space is saved, and installation ofa balcony and an outdoor air conditioner is convenient. For southern houses, an air passage of the hollow metal section supporting layer can adjust air circulation on the upper floor and the lower floor. The house simplifies beam and column nodes, and has the advantages of less construction process and convenient and quick installation. The house also has the advantages of simple and reasonable structure, safety and reliability, short site operation period, convenience and practicality, wide application range, and the like.