Abstract: A chaotic-pulse hybrid signal optical time-domain reflectometer(OTDR) was developed. The working principle is to measure the Fresnel reflection and backward Rayleigh scattering in the fiber by continuous chaotic light and discrete pulsed light respectively, and finally to obtain the optical fiber fault measurement curve by linear superposition of the measurement results. The instrument can solve the problem that traditional chaotic optical time domain reflectometer can not measure fiber loss events. By using G.652.B single mode fiber as the test fiber, the parameter specifications of the instrument are tested and analyzed. Results show that the instrument can realize a range-independent resolution of 35 cm within at least 104 km. The instrument also has a good detection effect on fiber loss events.