Abstract: Laser holography was used to measure the fuel spray characteristics of heavy jet kerosene and conventional aviation kerosene downstream after a simple orifice injector.The spatial distribution of droplet size and Sauter Mean Diameters (SMD) for two kinds of kerosene have been obtained and compared.In this paper,the effects of air velocity and pressure drop on the fuel spray field are considered.The following conclusions are drawn from the experimental data:1.The magnitude and distribution of droplet size are determined by the air velocity.2.The SMD for the two fuels are,to some extent,related to the fuel pressure.3.The variation of the fuel pressure has less influence on the SMD of the two fuels.4.The empirical formulas are provided for evaluating the effects of the air velocity and the fuel pressure on the SMD.