Acoustic Inkjet Printing (AIP) is suitable for jetting a small drop when compared with other available methods because the drop size depends not on the nozzle area but on the frequency of acoustic beam that enables ejection from free liquid surface.For inkjet printing, drop modulation is the major technology being effective to realize both high image quality and high print speed. In the previous reports regarding AIP, multiple droplets were fired at the same location on paper for gray scale of image.1 This method could enhance image quality at the sacrifice of print speed.Here we propose a method of drop size modulation in AIP to achieve both high image quality and high print speed. It has been proved that the drop size is modulated by a second harmonic on fresnel lens without changing the liquid level and other dimensions. This report also shows that calculations and experiments ascertained drop modulation by the second harmonic.