Corrosion in natural gas well tubing is a serious factor in failures of sour gas well under coexistence of H2S and CO2. In order to satisfy the need of long term safe production, this paper proposes the methods of tubing sizes optimization and material selection of tubing for preventing corrosion in high sour gas field under coexistence of H2S and CO2. Nodal system analysis is used for optimization on tubing sizes for preventing corrosion, which is mainly for preventing erosion. For material selection, traditional method is using sulfur-resistant steels. This paper proposes a new option: using corrosion-resistant alloy. By analyzing of chemical corrosion test, traditional sulfur-resistant steels may have severe corrosion in high sour gas wells under coexistence of H2S and CO2. For high sour gas wells under the severe corrosion environment with high hydrogen sulfide and carbon dioxide content, selecting corrosion-resistant alloy is a good method. This paper optimizes the corrosion-resistant material selection by taking YB-3 gas field as an example,. The experiment results show that there have serious galvanic corrosion and electrochemical corrosion by corrosion coupon test and galvanic corrosion test for sulfur-resistant steel. The corrosion-resistant alloy tubing may have a high initial investment; however, it has a very high safety and a low long-term operating cost, and has no need for adding chemical corrosion inhibitor. For high sour gas fields under coexistence of H2S and CO2, this measure can provide high cost performance and has a high resistance to corrosion. The study above has a good applicability by testing, and can provide reference for corrosion preventing of the similar high sour gas fields under coexistence of H2S and CO2.