With the rapid development of optical fiber technology, optical fiber networks have been deployed in aerospace, ships, data centers and industrial internet of things. Due to the principle limitations of traditional optical time domain reflectometer (OTDR), it is difficult to achieve high-resolution testing, and its application is limited in the above mentioned complex scenarios. Optical frequency domain reflection (OFDR) technology based on Rayleigh scattering can achieve extremely high spatial resolution, high sensing sensitivity and fast testing rate. The products are suitable for testing and troubleshooting of optical devices, optical modules and short-range optical networks, enabling insertion loss, return loss and length measurement across the entire range from the device to the optical link. A set of optical fiber link detection system is designed and implemented based on OFDR principle. The main problems such as polarization fading effect and nonlinear sweep frequency of the laser are studied. And the spatial resolution of 20 μm is achieved on 112 meters of the testing link.