Abstract: During the exploration of the Shanganning basin, the casing program was gradualy optimized,which at present is performed with the ?273mm surface casings running to 500m, shutting off the over laying water zone, inclining zone and leakage zone, and the ?177. 8mm production casing run for the final completion. This paper domenstrated the importance and feasility of selecting casing program, recommended the well drilling and completion technologies by Changqing oil field over a few year of efforts,which made it possible to drill safely and rapidly in the long open sections located in multi-layered and multi-pressured formations,while these techologies could prevent the formation from being damaged. It is believed that the optimized casing program is not only the best way to develop the gas field in central Shanganning basin economically and efficiently,but also made it possible for the repairing of corroded casings the recovery of replacement formation.