Abstract: The axial forces of vertical struts of the main beam and the plate bottom for a super high or large-span formwork support was measured on site during the period of casting concrete.The results showed that axial forces of vertical struts increased significantly after pouring the concrete above them, pumping had not only horizontal impact force but also vertical impact force, axial forces of vertical struts were uneven along the height, yet it was still safe to calculate the axial forces of the vertical struts by the regional load calculation method in the current code.There was an interaction between each tube of the formwork support, pumping and concrete placing route would induce horizontal force that would produce unfavorable effect on the stability of formwork support.According to the measured results, the present design and calculation method should be modified, and several effective suggestions on the construction of super high or large-span formwork support with fastener steel tube were provided.