In order to acquire an accurate aero-engine stability response model against airflow inlet distortion, the following steps are taken.Analyzing the stable total-pressure aberrance and turbulence distribution produced by the inserted-board airflow inlet distortion of a turbofan engine.Transforming the stable total pressure distortion and section pulse pressure into pressure-exciting waves at a set of frequencies.Through frequency spectrum analysis, the lowest steady pressure distortion waves' frequency and the biggest amplitude value are obtained, which are of the crucial factor that makes the engine lose its stability.Modifying the waves with a one-class response model and a parallel compressor model, a modified surging boundary is obtained.Calculating the high and low compressors' shifting process of operating points respectively when the engine is stalling gradually;Comparing the calculated result with that of the engine's experimental data, it is found that the results are similar.