The work aims to ensure the packaging accuracy during the operation of pre-forming mechanism and analyze the change law of support rod vibration response when the parameters change, including the weight of transverse sealing device, initial position, stroke and cycle. The transverse sealing device and support rod were simplified as double moving mass and flexible-beam system and the corresponding coupled vibration equation was established. The coupling system dynamic response was solved with the MEWMARK-β method under the given conditions and the change law curve was made by Matlab. When the transverse sealing device was in sinusoidal reciprocating motion, the mid-span deflection of the support rod was in sinusoidal vibration. The vibration response of transverse sealing device and support rod coupling system of the brick packaging machine was related to the weight, position and stroke of the brick packaging machine support rod. The vibration response of support rod can be reduce by reducing the total mass of the transverse sealing device, adjusting the initial position of the transverse sealing device and shortening the working stroke.