Abstract: Pressure testing on a 100 000 m³ floating roof oil tank with seawater is carried out in Dalian State Petroleum Reservoir. In the light of shortage of potable water as pressure testing medium, seawater pressure testing program is proposed. To control corrosion induced by seawater, a pressure testing technique of "temporary protective paint spraying + aluminum alloy sacrificial anode combined with seawater filtering thinning" is utilized, which can effectively control seawater corrosion to tank plates.