Abstract: To analyze the dynamic characteristics of disc head horizontal tank and to understand the effects of jacket holder on the natural frequency and vibration mode of storage tank, a finite element model suitable for the disc head horizontal tank was established by combining the modal analysis theory of vibration mechanics with the finite element method. Based on this model, the effects of spacing and number of jacket holders on the dynamic characteristics of storage tank were analyzed and the optimal spacing and number of jacket holders were obtained. It is indicated that the natural frequency of two-holder horizontal tank increases with the increasing of holder spacing, but its increase is not obvious any more after the holder spacing is half the length of the storage tank, so the holder spacing is the optimal when it is half the length of the storage tank. The natural frequency can be increased effectively and the deformation amount can be decreased if the number of holders is increased, but the vibration characteristics of the structure don't change much when the number of holders increases from three to four. Considering the cost of material and installation, therefore, three-holder horizontal tank is the optimal selection of multi-holder horizontal tank. The research results provide the theoretical basis for the holder design and engineering installation of horizontal tank.