The behaviors of linkage of built-in insulation reinforced concrete composite wall subjected to gravity load were experimental studied in this paper. The gravity load was computed as the sum of self-weights of thermal insulation layer, external concrete cover and surface decoration materials. Steel tube with square section was designed as the linkage. Two specimens modeling practical RCCW were cast and tested in Lab, many rectangular steel plates were used to simulated the uniformly distributed load on surface of external concrete cover. The relative displacement between inside structural reinforced concrete wall and external concrete cover, the strains of surface concrete and steel tube walls were measured. Tests were finished when load was over 3.24 times of design value, no relative displacement and only smaller concrete strains were observed, maximum tensile and compressive stresses of steel tube walls were only 6.3 % of design strength. It is concluded that the linkages are safe and the entirety of RCCW is good enough to satisfy the design requirements.