<p>The O-ring damper is commonly used to suppress the nonlinear vibration of the rotor system. In order to clarify its vibration reduction performance, it is very important to study the nonlinear damping and stiffness characteristics of O-ring. This paper first obtained the viscoelastic parameters of the O-ring material through relaxation and sweep frequency tests, comparing the applicability of two sets of viscoelastic parameters. Subsequently, experiments were conducted on the O-ring damper to validate the accuracy of the three-dimensional numerical simulation and viscoelastic parameters. Finally, based on the verified model precision, the influence of frequency, compression ratio, eccentricity, as well as the O-ring's inner diameter and wire diameter on the dynamic characteristics of the O-ring damper was analysed. The results show that the stiffness and damping of the O-ring vary nonlinearly with frequency, and at high speeds and high eccentricities, the damping of the O-ring decreases significantly, reducing its vibration reduction capability. An increase in compression ratio leads to an increase in the stiffness and damping of the O-ring, while the nonlinear behavior of the stiffness becomes more pronounced. Additionally, an increase in compression ratio weakens the influence of eccentricity, with the impact of compression ratio being greater at high frequencies than at low frequencies, while damping exhibits the opposite trend. When the inner diameter and wire diameter of the O-ring increase, both the stiffness and damping of the O-ring rise. This study systematically elucidates the dynamic response mechanism of O-ring dampers, providing theoretical foundations and parameter guidance for their optimised design and application in engineering. This contributes to enhancing vibration suppression efficacy and operational stability within rotor systems under complex operating conditions.</p>