Gas-turbine inlet dynamic total pressure flow field was measured to analyze the reason of surges happened during previous engine tests.Inlet flow field characteristics were obtained such as larger eddy scale and higher instant pressure distortion and pressure fluctuation associated with rotor speed base frequency which caused by the resonance of the engine and the inlet scroll case etc.Experimental data and information show that inlet dynamic flow field characteristics of the above-mentioned will make the engine increase the loss of stability margin and result in the engine surge.