Sinking and floating motion control is an important means to improve the quality of mariculture cages and ensure the safety of aquaculture. However, it is difficult to achieve accurate sinking and floating control due to multiple factors such as complex sea conditions and uneven loads. Aiming at the problem of sinking and floating control of a mariculture cage, this paper carries out modeling and collaborative control strategy research. Firstly, based on the analysis of the characteristics of cage structure, actuator and other objects, the dynamic model of sinking and floating is established. Secondly, based on the principle of parallel drive, a double closed-loop master-slave cooperative cage sinking and floating motion control strategy is proposed : the outer loop realizes the cooperative water inflow planning of multi-ballast tanks based on PID master-slave synchronization strategy ; the inner loop designs an efficient water inlet controller based on fuzzy sliding mode control and Lyapunov theory. Finally, through multi-condition digital simulation, the ballast tank water control algorithm and the cage sinking and floating cooperative motion control scheme are verified. The research results show that the control algorithm proposed in this paper can realize efficient water inflow control of ballast tanks, and can achieve high-precision sinking-floating coordinated control under different wave disturbances, which can provide technical support for practical applications.