To address the issue of high-precision cross scale detection in precision manufacturing industries such as chips and aviation components, a dual-field-of-view image-side telecentric microscope based on a single moving group is proposed. Firstly, a theoretical analysis is conducted on the imaging principle of the variable magnification microscope optical system, and a mathematical model for image-side telecentric variable magnification imaging based on a single moving group is established. Then, based on the variable magnification imaging model, a calculation method for the initial structure of the optical system is proposed, and the initial structure of the optical system has been calculated. Finally, using optical design software Zemax for lens replacement and optimization design, a common-aperture dual-field image-side telecentric microscope optical system has been obtained. The working spectrum of the microscope optical system is 1000~1700nm, with a magnification ratio of 4×, a working distance of 50mm, and a maximum object-resolution of 4.2μm. The analysis results show that the image-side telecentric error of the optical system is less than 2.0mrad, and the microscope optical system has the advantages of good imaging quality, low distortion, and simple zoom structure.