Abstract: Capacity at 10×10⁴ m³ floating roof oil tank is a kind of large-scale oil storage device used widely in China. To obtain stress distribution in key positions and check design rationality and operation safety, the field water filling stress test and finite element simulation calculation are carried out. The electrometric method is used through the combination of vibrating wire strain gauge and resistance strain gauge. As shown from the test results, the tank body reaches the maximum working pressure at the depth of 20.2 m, maximum circumferential stress occurs on the No.3 plate and below the No.4 plate of tank wall and testing value is basically consistent with the simulated calculation value. The oil tank is evaluated based on analysis design standard to show the oil tank is reasonably designed and its stress level can fully meet strength requirements under normal operating conditions. Testing methods and results can provide a reference to the design and testing of future 10×10⁴ m³ and larger oil tanks.