Abstract: Drilling as an important part in exploration and development process, costs more than 50% in the investment of it, while the well structure of drilling is one of the main factors to impact the cost of drilling. Based on the analysis and summary of block formation and pressure, and considering the drilling complex accident and well structure relationship, under the premise of ensuring the safety of drilling, the casing program have been optimized and simplified. Implemented by 2009, the consumption of the casing weight, cement quantity and the debris mining quantity per myriameter has a significant reduction compared with the consumption before optimization, so that the drilling Dagang Oilfield drilled economic and technical indicators and indicators of well structure optimization significantly improved than in the past, it also improves comprehensive benefits of oil field exploration and development.