To conduct experimental research on the dynamic response of submerged floating tunnel structures, this paper developed a device capable of controlling and instantaneously releasing the initial displacement of submerged floating tunnel structures. Additionally, the device can measure the acceleration and velocity of the entire vibration process. Subsequently, theoretical analysis methods were used to theoretically validate the experimental results of frequency and attenuation duration. The influence of different initial displacements on the frequency and attenuation duration was investigated. This study investigated the influence of different initial displacements on the frequency and attenuation duration. The experimental results showed that under initial displacements of 2 cm, 4 cm, and 6 cm, the frequency was not affected by the initial displacement, with errors all being less than 6.5%. However, as the displacement increased, the attenuation duration shortened, with the shortest attenuation duration being only 2.9 s.