Abstract: Owing to the fact that there is no applicable uniform and authoritative standard,further development of the C110 casings as created to meet the needs for exploration of H₂S-containing deep wells and hi-temperature & hi-pressure oil/gas wells has been restricted.Fortunately,thanks to their 8-year long efforts by relevant ISO/API committees,the standard for C110 casings has been drafted.Closely following the recent progress in the standardization of the said casings,studies are made by the co-authors.Briefed in the paper is the main information about the technical requirement as specified in the said standard draft.