In response to the challenges faced by traditional microscopy systems, which require multiple imaging and the use of image stitching techniques when covering large-area pathological slices, a large-field zoom microscope optical system has been designed. By ingeniously combining a large-field microscope objective and a zoom tube lens, this system achieves a single imaging of pathological slices, thereby obtaining complete information about the slices. By adjusting the magnification of the zoom tube lens system, it is possible to observe suspected lesion tissues in detail. The large-field microscope objective and the zoom tube lens were optimized using ZEMAX optical software. The design results show that the combined system has a focal length range of 90~800mm, achieving a 12x zoom, a working distance of 100mm, and a resolution of up to 3.45μm. Across the entire field of view, the Modulation Transfer Function (MTF) is greater than 0.3 at 75lp/mm, approaching the diffraction limit, indicating high resolution. An experimental system was set up to test the imaging performance of the large-field microscope objective, and the results demonstrated excellent lens quality, with a maximum object field of view reaching 18mm×18mm. This enabled the observation of large samples from details to the overall picture, significantly improving the detection efficiency.