Taking the hydropower symbiosis seawater desalination new technology system of a coastal steel enterprise as the subject, this paper addresses the challenges of using the steam turbine's exhaust steam as the heat source for low-temperature multi-effect evaporation seawater desalination within a system where the steam turbine generator set is closely coupled with the seawater desalination unit, presenting significant difficulties in joint safety control and a lack of technical solutions. From the perspective of prioritizing equipment safety, this paper designs safety control strategies suitable for the hydropower symbiosis process, including start logic, equipment safety interlocking protection logic under equipment failure conditions, and mode switching protection logic for the seawater desalination unit during low steam turbine load scenarios, enabling bidirectional interlocking protection for the steam turbine generator set and the seawater desalination unit. The practical application of this technical scheme at a certain coastal steel plant demonstrates that the designed hydropower symbiosis safety control strategies can achieve a safe and orderly start-up of the entire system. In the event of equipment failure, it can realize a bidirectional safe interlocking shutdown of the main equipment system, capable of stopping the seawater desalination unit in conjunction with the failure of the steam turbine generator set, and vice versa. Concurrently, the safety strategy can adapt to the needs of large load adjustments of the steel plant's gas supply, with significant effects on safe operation.