Design theory of high or large-span form strut system cann’t meet the engineering requirement and deficiencies were pointed out. In this paper, variation rule of axial force of the strut with the whole course of concrete pouring had been studied by measuring on three sites. The result discovered that pouring method and floor modes have significant effect on axial force of high or large-span form strut system. Compared to manual pouring, pumping lead to not only horizontal impact force but also vertical impact force. Compared to flat roof, axial force of avertical strut in sloping roof form strut system were more uneven and the maximal difference reached to 2 times. Axial force between bottom part and top part at avertical strut are different due to the influence of horizontal strut and crossing strut. Due to analysis result, some corresponding advices were put out in the end.