The present invention discloses a dynamic modeling method for a suspended liquid filling tank, and belongs to the field of spacecraft dynamics modeling and analysis. The ''shell + beam + concentrated mass point elements'' dynamic modeling method for the suspended liquid filling tank is adopted, a tank section connected with the support boundary is simulated by using the shell element, and other tank section is simulated by using the beam element; and in addition, in order to ensure a relatively large stiffness after pressurization of the actual tank, the multi-point constraint RBE2 is established on the upper and lower end surfaces of the shell element, and according to the method of consistency of the center of mass, the liquid is attached to the beam element in a corresponding position by using the discrete concentrated mass element. Compared with the traditional ''beam element'' and ''shell element'', the method disclosed by the present invention combines the advantages of different elements, so that on one hand, the connection stiffness between the tank and the main structure is not changed, both local modalities and feature point peak response are taken into account at the same time, and the consistency of the obtained modal and dynamic response predictive value and experimental value is better.