In this paper, a three-group inner-focus zoom system using dielectrowetting-based triple liquid lens and conventional fixed lens is proposed. When the first and the third components are fixed, the focal length of the system is changed by moving the intermediate liquid lens group. The self-zooming property of the liquid lens is realized to maintain the image plane. The initial structural parameters of the system is deduced by the optical power Gauss brackets method. The optical system is designed and optimized by Zemax software, and then the image quality of the system is analyzed. Results show that the system can achieve continuous zoom in the range from 2.7 mm to 20.3 mm; the total length of the system is decreased to 22 mm; the zoom ratio reaches 8 and MTF value is more than 0.4 at 180 lp/mm.