The safety and reliability of hydrological tower play an important role in the security and accuracy of the hydrological measurement. In order to simulate the space mechanical characteristics of the composite structure of tower with guy lines accurately, the finite element program is used to establish a precise three dimensional space finite element model. The structural strength and stability was also analyzed. Meanwhile, the static performance and vibration characteristics of the tower with guy lines was compared with the ones of the tower with none guy lines. The results show that the mechanical characteristics of composite structure are similar to the ones of continuous beams with lateral bearing spring. The guy lines rationalize the force distribution on structures, enhance the structural bearing capacity, and increase the structural stiffness. In addition, the paper can be a reference for the analysis of hydrological towers in aspects of numerical analysis, design methods and data.