Well Yingshen 2 is the deepest natural gas exploration well of Daqing oilfield, which was finished drilling in 2008. According to the characteristics of Songliao area and based on the analysis on the main factors which affected drilling speed and safe drilling, research of optimized drilling design was made. Optimization design on well structure, optimal selection of bit and drilling technology were carried out for well Yingshen 2. The record was set for deep natural gas exploration well of Daqing oilfield with over 5500m depth, exploration breakthrough was made with nitrogen and oil-in-water fluid under-balanced drilling technology; low yield gas flow was obtained in the midway test and commercial gas flow was obtained while drilling completion.