A sleeve for absorbing moisture from lenses is revealed. A sleeve body is divided into an upper space and a lower space for mounting a lens by a partition. A mounting cavity in which a moisture absorption material is disposed is in the upper space. An upper cover with a moisture detecting unit is fastened on an open end of the mounting cavity. The lower space provides a stretchable space to have a tight fit on the lens with different sizes. The moisture absorption range of the moisture absorption material extends to the periphery of the lens through air channels so that the moisture absorption material absorbs moisture from the lens through gaps of a lens end, a focus ring, and an iris ring of the lens for keeping the lens dry. The moisture detecting unit allows users to replace or treat the moisture absorption material in time.