Abstract: This paper deals with tests on Double Row Cascade diffuser mounted on the 45GP130 high Pressure ratio tunbocharger used for diesel locomotive at 3600m above the level of sea (design condition: Pressure ratio = 3.5: l; mass flow = 3.5kg/s. ) Two different impellers K1 and K2 are used alternately in the compressor for various matching tests. Out of theese tests optimum performance is chosen to compare with the result of test on single row triangular diffuser and comparative characteristic curves of the compressors are plotted, from which the advantage of the double row cascade diffuser is apparently manifested. In addition, the design principles and choice of parameters of the double row cascade diffuser are also presented.