In order to adapt to the present situation of the global oil and gas low price and reduce cost and increase efficiency more effectively, the design characteristics of the offshore platform fire water system are summarized and the relevant optimization measures are put forward according to the design results and experience of the built offshore platform fire water system. Adding the fire barrier in the biggest fire zone to minus the fire water demand is the effective manner, and the technical demonstration is carried out. The economic benefit is also analyzed, and millions yuan could be saved. The research provides reference for the design optimization of the offshore fire water system.