Abstract: Based on biological vision system, the variable focus liquid lens without any mechanical moving unit has lots of advantages, compared with conventional zoom systems, such as smooth zoom, little volume, light weight, simple fabrication and low cost. Therefore, it will have many potential applications in many fields. The variable focus liquid lens can be realized with three ways. The mechanically-actuated variable focus liquid lens, whose liquid surface curvature is controlled by a stepping motor, was designed and tested. The tested result shows that the variance of the focal length is accordance with the analitical result of CODE V. By putting the liquid lens in front of a fix-focus digital camera, the defocussing range of the system can be adjusted, and the zoom imaging can be realized. Finally the liquid lens has shown a satisfactory effect of imaging.