According to the requirement of high-quality fiber fusion in the process of optical fiber fusion, a microscope objective for detecting the fiber core is designed to determine the position of the optical fiber core, which is optimized through the optical system design software Zemax. The designed system consists of six lenses. The magnification is eight. The object space NA is 0.25. The working distance is 13.4 mm. The conjugate distance is 85 mm and image receiver is a CCD. The optical lens is optimized through the method of forward optical path with the spectral range of 486～656 nm. Forward optical path design of the microscope objective is practical to detect the fiber core position more clearly and accurately. It has long working distance, short conjugate distance and high accuracy.