Dynamic range and spatial resolution are the key indexes of optical time domain reflectometry(OTDR) system. On the basis of expounding the relationship between OTDR dynamic range and spatial resolution, this paper summarizes the new methods of improving OTDR dynamic range and spatial resolution at present, including pulse code modulation, OTDR signal processing algorithm, linear optical sampling method and chaotic optical time domain reflection method, introduces the research progress of these methods at home and abroad, and the future of improving OTDR dynamic range and spatial resolution is also prospected.