The control of sinking and floating is an important means to improve the quality of mariculture cages and ensure the safety of aquaculture. However， it is difficult to achieve the accurate control of sinking and floating due to multiple factors including the complex conditions of sea and uneven loads. Modeling and strategies for coordinated control were studied to solve the problem of controlling the sinking and floating of mariculture cages. A dynamic model of sinking and floating was established based on analyzing the characteristics of the structure of cages， actuator， and other objects. A dual closed-loop master-slave strategy for cooperatively controlling the floating of cages was proposed based on the principle of parallel drive. The outer loop implemented collaborative water inflow planning of multi-ballast tanks based on PID master-slave synchronization strategy. An efficient water inlet controller was designed for the inner loop based on fuzzy sliding mode control and Lyapunov theory. The water inlet control algorithm of the ballast tank and the scheme of cooperatively controlling the sinking and floating of cages were verified by digitally simulating the multiple conditions of working. The results showed that the control algorithm proposed achieved efficient water inflow control of ballast tanks and coordinated control of sinking and floating with high-precision under different disturbances of wave. It will provide technical support for the practical applications of the coordinated control of sinking and floating of mariculture cages.