Abstract: The toppling of a vertical slender rod occurs in a short period of time, the mechanical analysis of this process is made in this paper. Firstly, a theoretical model of the cylindrical rod, the hollow cylindrical rod, the rod with variable cross section and the rod with a mass on the top is constructed. Then, based on experiments, the strain distribution along the axis and the variation of the strain in these rods are obtained,which are found to be consistent with the theoretical model. Finally, the distribution and the variation of the strain in a toppling vertical slender rod are obtained.