Abstract: The structure and working principle of CQMPD fine pressure controlling drilling system are introduced, and its application example in Sichuan-Chongqing gasfield is given. The successful application of CQMPD fine pressure controlling drilling system in Moxi-Gaoshiti area in Sichuan and Chongqing, Jiange area in Northwest Sichuan and the right bank of Amu River in Turkmenistan effectively solved problems in drilling well control such as narrow safe density window, frequent lost circulation, overflow and even blowout, which plays an important role in the efficient and safe development of latent carbonate gas reservoirs. The maturity of the technology have proven very high. However, as exploration and development objects become more and more complex, the requirements for fine pressure controlling drilling technology are more stringent. In recent years, new development has been made in fine pressure control drilling technology, products and application fields, effectively improving the cementing quality of ultra-deep complex wells. This study also has important guiding significance for reducing drilling costs in developing complex pre-salt gas reservoirs.