A zoom optical system based on liquid lens is designed to solve the problems of security mechanical zoom system, such as large volume, complex structure, and easy wear. Under the Gaussian bracket theory, ZEMAX and MATLAB software are employed for the optimal design of the optical zoom system and to evaluate its imaging quality. The results show that the optical system achieves the continuous zoom function within the range of 20?80 mm, with a corresponding zoom ratio of 4. The total length of the system is 108 mm, F number ranges from 2.5 to 8, and the field of view ranges from 10° to 24°. When spatial frequency is 80 lp/mm, its modulation transfer function across the entire field exceeds 0.35, and the distortion levels remain below 2%. This optical system has the advantages of fast response speed, no mechanical parts, and strong zoom ability, promising significant upgrades and enhancements to intelligent security monitoring systems.