Abstract: The F Gas Field in Yinggehai Basin of the South China Sea is an HTHP gas field, characteristics of high temperature, high pressure and high CO₂ content has been the challenge to the integrity of wellbore, so the completion method was selected pertinently according to the characteristics of reservoirs. Based on the principle of keeping both the safety and the economy, the tubing/casing has been made by modified 13Cr material, and designed the different types of production strings. In terms of the characteristics of gas field and the development requirements, the selection of wellhead Christmas trees and downhole tools was carried out properly, the perforation pipe string was designed, and the proper annulus protection fluid was developed. In the end, it formed a completion technology suitable for the development of HTHP offshore gas fields with high acidic gas content. This completion technology has been applied in more than 10 wells of this gas field, and no sustained annulus pressure was observed during the production process, which indicated that the developed completion technology could effectively ensure the wellbore integrity of such gas fields, and provide supports for the large-scale development of HTHP gas fields in the Yinggehai Basin.