Flow visualization technology with particle image velocimetry system was applied in the paper to study the mixing flowfield of gas-gas injector. The method of tracing two different flows separately was adopted and three typical injectors

such as coaxial shear injector

coaxial swirl injector and triple impinging injector

were selected to conduct out a series of tests. The experimental results validate the way to trace the two flows separately credible and show the different mixing mechanisms of three typical injectors with axial and cross-section images

which reveal the major impact factors of mixing process and distribution features of mixing flowfield.