Flushing technology is an important link in drilling engineering. Circulation of flushing fliuid in the hole can clean hole bottom, cool drill bit, carry & suspend cuttings and protect the hole wall. Different flushing processes can produce different complicated situations. Due to the same direction of reverse circulation of flushing fluid at the bottom hole and the core entering into the core barrel, the quantity and quality of cores can be improved in the fissured, fractured, brittle and unequal hardness formations. Doctor KULIKOV V.V., who works in Moscow State Geological and Prospecting University in Russia, and some others have carried out a lot of scientific works in the hole flushing technology, present the classification table of compicated flushing situations in drilling process, analyze and discuss the flushing technology in geological drilling with commonly used drilling with no pump technology, jet core drill and air-lift core drill, and some correspongding suggetions are put forward.