Abstract: Based on the features and specifications of the visible optics for a detection system, the selection of optical layouts, the parameter calculation of initial layout and the method of aberration balance for a long focal length, largeaperture optical zoom system are introduced. The optical system design incorporated with mechanical compensation is presented. The image quality test, scene imaging evaluation and environment test for the optical system were carried out. The test result shows that the optical system designed with this method meets the system requirement.