Based on the demand of high pressure ratio turbocharging technology for modern high power density and low emission engines, the technical developments of single stage turbochargers with high flow and high pressure ratio in world famous companies such as ABB, IHI, KBB,MAN B&W and MTU were introduced. For the problems such as narrowed effective operating range, low efficiency and reliability deterioration due to the rising pressure ratios, the design features of high pressure ratios
turbocharging technology were finally summarized.