Abstract: To remove difficulties encountered in design of wellhead pipelines for high-pressure and high-CO₂ gasfields, ASME B31.3-2012, API 6A-2010 and ASTM A182-2004, ASTM A453-2000, ASTM A194-2000, ASTM A790-2000, ASTM A815-2001 standards have been combined to generate principles and methods for design of wellhead pipelines in high-pressure and high-CO₂ gasfields. According to the design, duplex stainless steel shall be used for fabrication of relevant pipelines. All large-sized pipelines shall be connected through welding with no on-line tapping allowed. At the same time, all branches of minor pipelines shall be connected by using flanges. In addition, hydraulic strength of the pipeline can be determined through calibration of yield strength of relevant materials. Furthermore, other innovative techniques have been deployed. The newly-developed design technique has been implemented successfully for design of wellhead pipelines on WHPF in DF-1-1 Gasfield in South China Sea. Currently, all wellhead pipelines of the gasfield are in sound conditions. Relevant research results may facilitate the development of high-pressure and high-CO₂ gasfields both offshore and in-land. In addition, these results may be used to regulate the construction of oil/gas gathering pipelines to enhance the safety and reliability of relevant projects.