The cargo oil pipeline system of general Floating Production Storage and Offloading (FPSO) is established by the dynamic fluid analysis software AFT Impulse. The steady state and transient analysis of the pipeline is carried out. According to the mechanism of water hammer, three optimization methods of extending the closing time, two-stage closing and adding surge tank are carried out to ensure the safety of the cargo oil system. The results show that the optimization method of adding surge tank is more effective.