Abstract: A brief view and results of tests for the effects of the inlet total pressure distortion on the performance and the stability of a two-spool turbojet engine are presented. There are a 3-stage H. P. compressor and a 3-stage L. P. compressor in the engine, in which two types of the first stage rotor G02 and 5P are tested separately. The distortion was generated by metallic mesh screens and the compressor surge was induced by a fuel flow step generator.It could be seen from the test results that when the area of the jet nozzle increases from 100% to 142%, the operating line of L. P. compressor falls significantly, no matter whether the inlet airflow is distorted or not.The engine with G02 or 5P first stage rotors has surged 42 times. The surge line and operating line were determined with and without distortion. Test results are given in relationship of the pressure ratio to corrected mass flow and corrected speed.The inlet distortion caused the surge line and operating line of the H. P. and L. P. compressors to be moved downward, and the surge margin decreased. The greater the distortion index, the steeper the surge line falls. When the distortion index increases, the operating line falls slightly, the loss in surge margin increases. The quantitative relationship of the above-mentioned trend is shown with curves of test data in the paper.Comparing the engine test results with the rig test results, the surge line of the L. P. compressor obtained from engine test is higher than that from rig test, no matter whether the inlet airflow is distorted or not. This confirms that the surge margin and the compressor characteristic lines are effected not only by the inlet conditions, but also by outlet conditions, the interaction between compressor and other components, the initial process of surging and the difference between quasi-steady flow and dynamic flow. The characteristic lines of an independent component could not be simply used as a substitute for that of the compressor coupled with other components in a engine. That is, the test results of certain component obtained on test rig under specified conditions could not be considered as a reasonable base for evaluation of its performance and stability in an engine system.