There are two patterns of palaeodrainages, the surface ones and the underground ones in Ordovician carbonate buried hills in Tarim Basin. They are closely relative with the distribution and development of caved and fractured karst reservoirs in buried hills. Underground drainages controls the distribution of large-scaled caves and has a great influence upon huge cracked fractures at the top caused by cave collapse during late phase. Surface drainages are generally erosive in high parts of buried hills and generally solvent in lateral or vertical in low parts while they can be solvent at the two sides and the bottom of drainages. Surface drainages can induce to form fractures due to differentiate compaction of fillings during late diagenesis. During development and evolution of the two patterns of palaeodrainages, they meanwhile play a role of enlarging dissolution to fractures so as to form larger scaled karst cave/fracture system. In the process of researching palaeodrainage patterns in carbonate buried hills, some key research methods are applied, such as the paleogeomorphic construction, the seismic attribute analysis, the frequency division processing, and the azimuth division prestack fracture detection.