This paper focuses on analyzing the influence of support clearance on the vibration characteristics of the plate cylinder, so as to optimize the structure of the plate cylinder. Some three-dimensional models of the plate cylinder with no support clearance and different clearances are established on SolidWorks software, and these models are imported into ADAMS software for dynamic analysis under operating conditions. The simulation analysis results illustrate that, compared with ideal no clearance case, the average contact force amplitude for the support clearance case increases from about 200 N to about 1000 N, and the fluctuation also increases. The corresponding displacement response changes irregularly, and the displacement amplitude also increases. Additionally, with the increase of clearance value, the above changes would be intensified. However, under the same clearance value, the increase of support thickness would weaken the aggravating effect of the clearance on the contact force and displacement amplitude of the plate cylinder. Therefore, the plate cylinder can be optimized by increasing the support thickness, so as to reduce the aggravating effect of clearance on the radial vibration of the cylinder and improve the printing quality.