With the continuous progress of technology and the rapid development of industrialization, automated production lines have become an important component of modern industry, and industrial lenses need to detect product appearance defects, size, position, and text information on high-speed assembly lines. In response to the problems of slow focusing speed and complex structure of traditional industrial lenses, this paper designs a long focus adjustable optical system with a large target area based on ZEMAX. The method uses a liquid lens to achieve millisecond level fast focusing effect and a more compact optical structure. The optical system has a focal length of 50 mm, a total length of 137.869 mm, a target area of 1.1 inches, a working distance of 300 mm to infinity, full field resolution is 145 lp/mm>0.3, distortion<1%, and can perform high-definition imaging and meet the basic requirements of part processing technology.