There are various types of liquid fuel injection system for aircraft propulsion. Among these, vaporizing system is widely applied to micro turbojet engine. The advantages of this device are simple, low fuel supply pressure and low price. However, this system requires preheating during initial startup and has relatively low combustion efficiency during design point operation. Recently, the development of micro gas turbine in Korea has been examined, but the spray characteristics of vaporizer have not been studied in Korea. Therefore, the spray characteristics of the vaporizer under various engine operating conditions should be studied. High pressure steam generator was used for fuel heating and combustor inlet air from the centrifugal compressor was simulated by compressed air stored in the pressurized air tank. Four types of vaporizing tube such as straight, swirler, guide vane and t-shape were designed. In order to know the injection characteristics of the vaporizer tube, spray visualization of one vaporizer was performed. Thereafter, six vaporizer tubes were installed and spray visualization was performed to confirm the superposition effect of the spray over the annular combustor. The spray angles with fuel supply pressure and air pressure difference were measured. In the results, guide vane shape has a wider spray angle than the others. The experimental results confirmed that the spray characteristics of vaporizer are affected by fuel supply pressure and combustor inlet air. Malvern Panalytical Spraytec apparatus was used to measure the size of spray particles. In the particle size measurements results, the guide vane shape was found to have the smallest particle size compared to other shapes. The spray visualization and particle size studies of the vaporizer provided a deep understanding of the spray characteristics of the vaporizer. As a result of the measurement of spray characteristics for various vaporizer shapes, the guide vane shape showed the best spray characteristics.