Abstract: There are a great number of gas-bearing reservoirs are buried shallowly in Tainan gas field. They are mostly thin and have poor diagenetic grade and loose structure. Accidents like sticking, collapse, leak, and blowout often occur during drilling. Through analysis, five systematic optimized drilling technologies are developed,i.e. optimal design of casing program, leak resistance and plugging technology, selection of salt/polymer drilling fluid systems, optimization of drilling technologies, cementing technologies. So drilling speed is increase remarkably. The average period of vertical well completion in 2008 was shortened by 40.43% as compared with that of 2007, while the average period of horizontal well completion was shorted by 45.51%, and 123.7635 million yuan of drilling cost was saved. The systematic technolgies meet the requirement of optimized drilling in Tainan gas field.