Abstract: Square cages are easy to incur a whole overturn and to sink unsuccessfully in close to the sinking critical state.The influence factors of turning on one side of a cage are analyzed through the study on dynamic characteristics of a sinking process of square cages.The major outer reason of overturn under wind wave and water current is the rotation torque.And the corresponding technical means are taken to construct the anti-overturn device composed of cross nets muscle and rigid support bar components on the basis of the original square cages.The stress state of cages during a sinking process is changed to realize the stable sinking of cages in bad sea conditions.The experiment and simulation results show that the sinking incline angle of a square cage assembled anti-overturn device is less than 27°.And the theory basis and method can be provided for founding and completion of a square cage sinking balancing technique.