The bottom frame of Flounder fish cages with double bottom floors would incline and rotate in current. To ensure the cage bottom structure safety, it is necessary to carry out dynamic analysis for the anti-current characteristics of the cages. Herein, based on the finite element method, a numerical model of the double-bottom cage deformation in current force is developed and then the maximum displacement and pitch of the double bottom are studied. In addition, the calculated results of double-bottom cage are compared with those of single-bottom cage. The simulation results show that the pitches of the upper and lower bottom floors increase along with the increase of flow velocity, and the dip directions of the two bottom floors are just opposite. It is found that when the flow velocity exceeds 93cm/s in sea, the upper and lower bottom floors of the cage would collide with each other and affect the safety of the cage bottom. Moreover, the displacement of the lower bottom of double-bottom cage is larger than the bottom displacement of the single bottom cage, but the pitch of lower bottom is smaller than the bottom pitch of the single bottom cage, which might be related to the design of the upper bottom of the cage.