Abstract: The anchored bracing pile is more widely and more applied beyond its theory. Dynamic data of steel bar stress and horizontal displacement along piles are analyzed, and the distribution rules of internal force and deformation are gained. Based on steel bar force and section curvature, two methods to calculate bending moment along pile are deduced. Comparison between the m method and the equivalent beam method indicates that moment distribution is similar, but its numerical value is very discrepant. The m-method has the largest bending moment, and the in-situ measurement has the smallest bending moment. So the traditional design methods have large optimization space. Theoretically it can save half quantities of steel bars, which are less collocated near the central axis.