Abstract: In this paper the design and implementation process of a seawater cooling system for a reef-type radar are discussed. And the corresponding technology solutions to the problems in the process are given. At the same time, the design idea of modular and distributed seawater cooling system is put forward according to the special environment of island reef in the South China Sea. The cooling system takes the seawater cooling as the main operation mode and the air cooling as the standby operation mode. The two modes can be automatically switched. Practice has proved that the seawater cooling system not only can meet the cooling requirements of the reef-type radar, but also takes into consideration the transportation, erection and unattended requirements of the island reef equipment.