Civil aircraft lightning test is necessary to verify the aircraft’s lightning protection capability，which is used to simulate the protection performance of an aircraft in a lightning environment by injecting a simulated lightning current into the test piece or test machine. For section-level and aircraft-level lightning tests, the amplitude of the simulated lightning current is usually controlled by the scaling current method for the protection of the test piece and the testing machine. This paper describes in detail the concept, purpose and conditions of application of the scaled current method. The reliability of the test results under different amplitudes of simulated lightning current injection was analysed for the current test, voltage test and surface magnetic field test as an example of metal wing box lightning test, and a more suitable amplitude of simulated lightning current was obtained. This paper has certain guiding significance for civil aircraft segment-level and aircraft-level lightning environmental testing.