The utility model discloses a formwork for improving pier durability in a freezing-thawing or chlorine salt erosion environment. The formwork comprises a pier formwork and a protective sleeve with high freezing-thawing durability and/or chlorine salt erosion resistance, wherein the sleeve is fixed on the inner wall of the pier formwork using a detachable connection structure; when concrete pouring for the pier is finished and formwork stripping conditions are satisfied, the sleeve and pier concrete are combined together, the pier formwork is stripped to separate the pier formwork from the sleeve, and the sleeve is left on the pier surface. The formwork provided by the utility model uses the predesigned sleeve with excellent durability as a protective measure for the pier, can be used for obviously improving the pier durability, speeding up the cofferdam circulation rate in the construction process, greatly shortening the offshore operation time and greatly saving the maintenance costs in the running process, and is obvious in technical benefit and economic benefits.