For the complexity of double- linkage zoom system, the design process is settled first, and the visible assist design software is developed. The function of the software includes Guassian optical calculation, compensation curve drawing, aberration and lens size analysis, relative aperture curve output, etc. Using the software, rational Guassian parameters can be selected conveniently, and the relative aperture and its variation of each group can be given, which can help the designer to select the initial configuration. Then utilizing the software, the initial design can performed for a double- linkage zoom system with focal length range from 25mm to 500mm. And through integrated optimization, the system aberration is corrected and balanced. The design results demonstrate that the total optical length is 478 mm, and the modulation transfer function (MTF) at 50 lp/mm for each zoom configuration is higher than 0.6 for center field, and higher than 0.4 for edge field. All indexes satisfy the command of system.