The droplet shape in the process of droplet dropping can embodies the fundamental intrinsic properties of droplet, which can be used to identify the characteristics of liquid types. A new method is proposed by using Moment characters- Fourier descriptor to analysis the information of droplet dropping image. Data of the droplet profile changing is collected through the CCD camera. Moment characters sequence is calculated to represent the shape. The sequence is given Fourier counterchanges and normalized. The feature descriptor carries the liquid image features and unique information of liquid.