At present, the national norms of temporary support structure in building construction has not officially promulgated. there was no uniform standard in the structure design and construction, which leaded to the collapse of construction accidents occurring from time to time. Through measuring mechanical behavior of support system of coupler, the statics have obtained that loads of temporary support has been gradually imposed on the structure by step construction in the construction process. Construction loading is a complex process of construction mechanics. The measured axial force is larger than standard one by JGJ130-2001. The results shows the load structure suffered has been not fully taken into account. As the load of erecting pole of top and bottom is not the same, the height of structure bearing capacity has been considered in design. As the second-order effecting on structure, both horizontal rod and bridging bear a certain horizontal force in the construction process. The value of bridging stress is larger. In the structure design calculations, the arrangement of bridging should be paid more attention to improve the stability of the entire frame. The obtained results provides experiment basis for support system designed.