To improve the safety and operating efficiency of underwater slender bodies, the hanging underwater slender body is divided into several micro segments for analysis. The equilibrium equations of each segment are listed according to the mechanical equilibrium and deformation coordination conditions. Then, the equilibrium equations are solved with MATLAB programming. When the upper end moves horizontally and periodically, the upper end motion amplitude, upper end motion period, and lower end weight are changed separately to obtain the amplitude envelope of hanging underwater slender bodies. Based on the results of numerical calculations, the response envelope characteristics of hanging underwater slender bodies are analyzed. The maximum amplitude point on the amplitude envelope of the slender body is generally at the upper end. As the parameters change, it can be converted to the lower end. Changing the amplitude and period of upper end motion has a greater impact on the minimum amplitude point. The lower end weight has a small influence on the minimum amplitude point. By adjusting the ranges of these parameters, the positions of maximum amplitude point and minimum amplitude point on the amplitude envelope of slender body can be controlled.