<p>Printing accuracy is influenced by the dynamic properties of the rubber layer on the paper feeding spindle. Due to the inherent complexity in precisely calculating the dynamic response of rubber, this work presents an approximate analytical approach. In this study, a nonlinear equivalence model was applied to rubber materials, treating the rubber and steel as an equivalent composite material. Modal analysis and calculations were then performed based on this model. The elastic modulus and Poisson’s ratio of the rubber were determined experimentally and used as inputs for the modal simulation. The computed modal characteristics of the composite spindle were compared with those of the steel spindle. Experimental modal analysis was conducted using the LMS test facility (Siemens vibration analysis software). Additionally, online vibration measurements of the rubber layer on the paper feeding spindle were taken using a laser vibrometer. The results indicated that the first two natural frequencies obtained from the simulation were close to the first two dominant test frequencies of the rubber layer with the highest amplitudes. This confirms that vibration of the rubber layer is the primary source of spindle vibration and validates the reliability of the laser vibrometer measurements.</p>