In theory,high compression ratio has the potential to improve the thermal efficiency and promote the power output of the SI engine.However,the application of high compression ratio is substantially limited by the knock in practical working process.The objective of this work is to comprehensively investigate the application of high compression ratio on a gasoline engine based on the Miller cycle with boost pressure and split injection.In this work,the specific optimum strategies for CR10 and CR12 were experimentally investigated respectively on a single cylinder DISI engine.It was found that a high level of Miller cycle with a higher boost pressure could be used in CR12 to achieve an effective compression ratio similar to CR10,which could eliminate the knock limits at a high compression ratio and high load.To verify the advantages of the high compression ratio,the fuel economy and power performance of CR10 and CR12 were compared at full and partial loads.The result revealed that,compared with CR10,a similar power performance and a reduced fuel consumption of CR12 at full load could be achieved by using the strong Miller cycle and split injection.At partial load,the conditions of CR12 had very superior fuel economy and power performance compared to those of CRI0.