The high security of civil aircraft is one important goal of airplane design. The fire protection function and fire extinguish function of nacelle is particularly important. According to airworthiness articles, this paper presents a ground test method which is suitable for nacelle fire protection system of civil airplane. In this method, a system based on micro-differential pressure was used to measure agent concentration in nacelle, and the test was carried out on the nacell fire extinguishing performance verification test bench which simulated the real internal and external shape and the flow field of true nacelle. At the same time, the hardest circumstances were simulated in order to verify the diffusion of fire extinguish agent of nacelle under the hardest test circumstances. In this test, high-accuracy sensors were used to measure test parameters, record the test data, and compare the test results according to FAA articles. It is proved that the method can effectively and accurately achieve the test goal of the nacell fire extinguish system by ground test. The test results can provide experience for the on-board test, and provide important reference for the configuration change of on-board nozzle and the layout of fire extinguish pipe network.