An optical time domain reflectometer based on chaotic signal correlation ranging technology (COTDR) is designed and developed. The chaotic light source, hardware configuration and software design of the system are presented. By using G.652.B single mode fiber as the test object, technical specifications of the COTDR for fiber fault location are tested. Measured results show that the COTDR can realize a range-independent resolution of 50 cm within at least 102 km, which is raised by about two orders of magnitude compared with the existing flight time measurement technology. Furthermore, it can realize the recognition of the different reflection events in the fiber and meet a requirement of fault location in the passive optical network.