A new type of Y-jet airblast atomizer was developed to control mean droplet diameter over a wide range of liquid flow rates. This atomizer employs a fluid amplifier system that controls the liquid delivery to two kinds of injection ports having different inner diameters. In order to clarify the effect of amplifier dimensions on spray characteristics, the relationship between flow rate characteristics and spray characteristics was investigated and flow visualization of the flow inside the fluid amplifier was performed. When the main flow rates were 3.0g/s and 4.0g/s, the flow rate characteristics of the amplifier were improved, and good spray characteristics were obtained.