Spray characteristics of a centrifugal two-nozzle injector were experimentally studied using the light integrating diaphragm method (LID) based on small angle laser light scattering. The theories on the small angle scattering were reviewed, which could be used to measure the size of liquid fuel droplets and the fuel concentrations. LID technique was successfully applied in one burner compartment in a test facility of gas turbine combustor. The measurement of Sauter mean diameter with LID method has an accuracy of about 5% for liquid fuel droplets. Kerosene or water sprays from the dual swirl fuel nozzle were tested under various conditions in terms of the fuel supply pressure and air-assisting. It was found that the droplet size decreases as the injection pressure increases and more when the injection is assisted by air. The experimental results imply that the low pressure air-assisted injection can simulate the realistic high pressure injection.