The spray characteristic of gasoline direct injection(GDI) injector strongly determines the subsequent fuel/air mixture formation, combustion and emissions. Systematic measurement of gasoline spray using the optical diagnostic method can obtain the macroscopic and microscopic characteristics of spray that are important to optimize combustion and reduce emissions. For a commercial 5 hole GDI injector, the high-speed diffused back-illumination photography, the planar high-speed Mie scattering photography and the phase Doppler interferometry(PDI) was respectively utilized to get the spray image, pattern and droplet size. Besides, the influences of thermodynamic boundary conditions including injection pressure, ambient back pressure, and injection duration on spray characteristics were analyzed. The results show that the increased fuel injection pressure would lead to a more concentrated spray pattern, earlier occurred spray plume interaction, longer penetration, larger spray angle in the early stage and more droplets with the size of smaller than 10 μm, and hence better spray effect. Increased back pressure had a worse spray effect due to the completely opposite influencing law. The influence of injection pressure and back pressure on the number of particles smaller than 60 μm is negligible. Increased injection duration would also lead to a more concentrated spray pattern and earlier plume interaction.