Abstract: The fire pit is a spatial element shared by the folk dwellings in the Han-Tibet-Qiang-Yi corridor. Through the dual evidence of literature and field, we have investigated the connotation and significance of its historical evolution, spatial layout, typological characteristics, living customs and spiritual beliefs, and initially clarified that it is a spatial carrier for multicultural intermingling and coexistence. Standing in the context of today's casting of a community for the Chinese Nation, through the archaeological data into the logic of the basic function of human fire from the construction of the fire space 'outdoor-indoor' displacement, and then from the plane of the fire space function and vertical structure of the fire space organization, found that the fire pit is its 'function-core' organizational link. On this basis, through the characterization of three different levels, namely, natural primitive, functional material and spiritual construction, the study reveals the historical facts of 'three crossings' in the ethnic areas under its architectural commonality. The study shows that the evolutionary logic of the fire pit is 'functionmyth-space', and there is the overlapping phenomenon of 'primitive worship' and 'blood relatives contact'. The conclusions of the study helped the practice of a community for the Chinese Nation consciousness project and promoted the development of local harmony.