In this paper, we mainly study the deepwater subsea pipeline arrestor design, and give the space calculation method for arrestors. The arrestor design includes wall thickness calculation and layout space calculation. The wall thickness design always follows the method given by the Det Norske Veritas (DNV) standard. However, there is no specific method for the space calculation in standards. Based on the analysis on pipe procurement and installation economical efficiency and risk assessment, we give a method for space calculation. This method has been successfully used in Liuhua pipeline project.