Liquid lens is a new type of opt electric device.Compared with the traditional solid lens,the liquid lens has many advantages such as fast focal length tenability and lower power consumption.So it can be used for the eyes of the bionic robot,fast tunable telescope system et al.In 2004,French Varioptic developed a practical liquid lens.At the same time,S.Kuiper coming from Philips Company also launched a focus liquid lens based on EWOD effect.Varioptics ARCTIC Series liquid lens only takes a maximum of 100ms for the focus that matches the distance to the photographic subject to go from 5cm to infinity.The devices listed above provide us an envident practical tendency of the liquid lens,but a clear designing dicipline is not well established at present,which will limit the scale of the lens manufacture.So its neccesary to embark the reserch on the the designing dicipline.The optical power is a important parameter in the lens performance hierarchy,so it plays a significant role in the designing decipline.It has been found that the optical aperture can affect the optical power,but until now,there is no research report on this effect.In this paper,the effect of the optical aperture on the optical parameters of the liquid lens has been analyzed,it is found that the optical aperture plays an impotant role on the optical power dynamic tuning range.The results have shown that it is important to the design of the liquid lens.