The Yuanba area in northeast of Sichuan is a key area for natural gas exploration in China. But the complicated geological structure, low penetration rate and long construction period, especially at the bottom of Ziliujing formation and Xujiahe formation, have always been the bottleneck restricting drilling speed in this area. According to the formation characteristics, diamond bits with different structures and properties were developed. The experiments showed good effects in the blade cutter and second insert bits matching with the domestic PDM. The drilling rate was improved with lower cost and shorter time.