Abstract: The compression and expansion ramps were designed to study the mixing performance of the different structured ramp injectors.The experiments of flame transfer,schlieren photograph and oil flow were conducted for the ramp injectors.The calculation fluid dynamics was used to simulate the pressure distribution,the interaction of shock and the forming of stream eddies following the ramps injection.The simulation results are coincident with the experiments.Finally,the differences between this experiment and the previous reports were analyzed.It's concluded that the expansion ramp of the two injectors has better performance of self-ignition and flame holding than the compression one.