Spray characteristics of gas-liquid coaxial shear and swirl injectors were studied by conducting experiments. The results suggest that the injector outlet expanding can improve atomization performance; for the two kind of injectors, that is, gas-liquid coaxial swirl injectors and gas-liquid coaxial swirl injectors, with a proper indent length，they have good atomization performance and proper flow performance; and under the same conditions, gas-liquid coaxial swirl injectors have better atomization performance than gas-liquid coaxial swirl injectors.