Abstract: To evaluate the performance of large-scale, low-frequency tuned mass dampers in practical civil engineering applications, a high-tonnage low-frequency low-damping and large-amplitude vertical vibration testing platform was developed. Based on the principle of inertial amplification, the platform achieves an equivalent mass of one kiloton using a physical mass of approximately ten tons. The system enables continuous frequency adjustment within the range of 0.085 Hz to 0.2 Hz and enables a maximum displacement amplitude of 20 cm. A flexible transmission conception is proposed to connect the mass block and the inertia. If the amplitude exceeds 3 cm, the damping ratio can be effectively maintained below 0.5%. The design idea and core technologies of the testing platform were described. The parameters of the vibration system of the platform and their adjustment methods were introduced. Large-amplitude free vibration tests under various frequency conditions were conducted, and the amplitude-dependent damping characteristics were analyzed. Typical forced excitations were generated using actuators to investigate the dynamic responses of the platform under various conditions. The platform provides a vital experimental media for the development of novel large-scale low-frequency damping and excitation devices, and holds great potential for widespread application.